What path does the electron follow in the electric field when the electron is projected normally in the field?

An electron passes through a space without deviation. Does it mean, there is no electric or magnetic field?

Is there any condition that an electron does not experience any force inside a magnetic field?

Are the specific charges of an electron and proton the same? Explain.

Oil has a density of 800 kgm^-3. A 1 $\rm\mu m$ diameter oil droplet acquires 10 extra electrons as sprayed. What potential difference between two parallel plates 1 cm apart will cause the droplet to be suspended in the air?

In a p-n junction, the depletion region is 400 nm wide and an electric field of \( \rm 5 \times 10 ^{5} Vm^{-1} \) exists in it. (a) Find the height of the potential barrier. (b) What should be the minimum kinetic energy of a conduction electron which can diffuse from the n-side to the p-side ?

The current–voltage characteristic of an ideal p-njunction diode is given by \[ \rm i = i_{0} ( e^{\frac{eV}{kT}} - 1 ) \] where the drift current \( \rm i_{0} \) equals 10 μA. Take the temperature T to be 300 K. (a) Find the voltage \( \rm V_{0} \) for which \( \rm e^{\frac{eV}{kT}} \) = 100. One can neglect the term 1 for voltages greater than this value. (b) Find an expression for the dynamic resistance of the diode as a function of V for \( \rm V > V_{0} \). (c) Find the voltage for which the dynamic resistance is 0.2 Ω.

Consider a p-n junction diode having the characteristic \[ \rm i = i_{0} ( e^{\frac{eV}{kT}} - 1 ) \] where \( \rm i_{0} \) = 20 μA. The diode is operated at T = 300 K. (a) Find the current through the diode when a voltage of 300 mV is applied across it in forward bias. (b) At what voltage does the current double?

When the base current in a transistor is changed from 30 μA to 80 μA, the collector current is changed from 1.0 mA to 3.5 mA. Find the current gain β.

A load resistor of 2 k Ω is connected in the collector branch of an amplifier circuit using a transistor in common-emitter mode. The current gain β = 50. The input resistance of the transistor is 0.50 kΩ. If the input current is changed by 50 μA, (a) by what amount does the output voltage change, (b) by what amount does the input voltage change and (c) what is the power gain?

Calculate the number of states per cubic metre of sodiumin 3s band. The density of sodium is \( \rm 10^{13} kgm^{-3} \). How many of them are empty ?

In a pure semiconductor, the number of conduction electrons is \( \rm 6 \times 10 ^{19} \) per cubic metre. How many holes are there in a sample of size 1 cm × 1 cm × 1 mm ?

Indium antimonide has a band gap of 0.23 eV between the valence and the conduction band. Find the temperature at which kT equals the band gap.

The band gap for silicon is 1.1 eV. (a) Find the ratio of the band gap to kT for silicon at room temperature 300 K. (b) At what temperature does this ratio become one tenth of the value at 300 K ? (Silicon will not retainits structure at these high temperatures.)

When a semiconducting material is doped with an impurity, new acceptor levels are created. In a particular thermal collision, a valence electron receives an energy equal to 2 kT and just reaches one of the acceptor levels. Assuming that the energy of the electron was at the top edge of the valence band and that the temperature T is equal to 300 K, find the energy of the acceptor levels above the valence band.

The band gap between the valence and the conduction bands in zinc oxide (ZnO) is 3.2 eV. Suppose an electron in the conduction band combines with a hole in the valence band and the excess energy is released in the form of electromagnetic radiation. Find the maximum wavelength that can be emitted in this process.

Suppose the energy liberated in the recombination of a hole–electron pair is converted into electromagnetic radiation. If the maximum wavelength emitted is 820 nm, what is the band gap ?

Find the maximum wavelength of electromagnetic radiation which can create a hole–electron pair in germanium. The band gap in germanium is 0.65 eV.

In a photodiode, the conductivity increases when the material is exposed to light. It is found that the conductivity changes only if the wavelength is less than 620 nm. What is the band gap ?

Let ΔE denote the energy gap between the valence band and the conduction band. Th e population of conduction electrons (and of the holes) is roughly proportional to \( \rm e^{\frac{- \triangle E}{2kT}} \). Find the ratio of the concentration of conduction electrons in diamond to that in silicon at room temperature 300 K. ΔE for silicon is 1.1 eV and for diamond is 6.0 eV. How many conduction electrons are likely to be in one cubic metre of diamond ?

The conductivity of a pure semiconductor is roughly proportional to \( \rm T^{\frac{3}{2}} e^{\frac{- \triangle E}{2kT}} \) where ΔE is the band gap. The band gap for germanium is 0.74 eV at 4 K and 0.67 eV at 300 K. By what factor does the conductivity of pure germanium increase as the temperature is raised from 4 K to 300 K ?

Estimate the proportion of boron impurity which will increase the conductivity of a pure silicon sample by a factor of 100. Assume that each boron atom creates a hole and the concentration of holes in pure silicon at the same temperature is \( \rm 7 \times 10 ^{15} \) holes per cubic metre. Density of silicon is \( \rm 5 \times 10 ^{28} \) atoms per cubic metre.

The product of the hole concentration and the conduction electron concentration turns out to be independent of the amount of any impurity doped. The concentration of conduction electrons in germanium is \( \rm 6 \times 10 ^{19} \) per cubic metre. When some phosphorus impurity is doped into a germanium sample, the concentration of conduction electrons increases to \( \rm 2 \times 10 ^{23} \) per cubic metre. Find the concentration of the holes in the doped germanium.

The conductivity of an intrinsic semiconductor depends on temperature as \( \rm \sigma = \sigma_{0} e^{\frac{- \triangle E}{2kT}} \), where \( \rm \sigma_{0} \) is a constant. Find the temperature at which the conductivity of an intrinsic germanium semiconductor will be double of its value at T = 300 K. Assume that the gap for germanium is 0.650 eV and remains constant as the temperature is increased.

A semiconducting material has a band gap of 1 eV.Acceptor impurities are doped into it which create acceptor levels 1 meV above the valence band. Assume that the transition from one energy level to the other is almost forbidden if kT is less than 1/50 of the energy gap. Also, if kT is more than twice the gap, the upper levels have maximum population. The temperature of the semiconductor is increased from 0 K. Theconcentration of the holes increases with temperature and after a certain temperature it becomes approximately constant. As the temperature is further increased, the hole concentration again starts increasing at a certain temperature. Find the order of the temperature range in which the hole concentration remains approximately constant.

In a p-n junction, the depletion region is 400 nm wide and an electric field of \( \rm 5 \times 10 ^{5} Vm^{-1} \) exists in it. (a) Find the height of the potential barrier. (b) What should be the minimum kinetic energy of a conduction electron which can diffuse from the n-side to the p-side ?

The potential barrier existing across an unbiased p-n junction is 0.2 volt. What minimum kinetic energy a hole should have to diffuse from the p-side to the n-side if (a) the junction is unbiased, (b) the junction is forward-biased at 0.1 volt and (c) the junction is reverse-biased at 0.1 volt ?

In a p-n junction, a potential barrier of 250 meV exists across the junction. A hole with a kinetic energy of 300 meV approaches the junction. Find the kinetic energy of the hole when it crosses the junction if the hole approached the junction (a) from the p-side and (b) from the n-side.

When a p-n junction is reverse-biased, the current becomes almost constant at 25 μA. When it is forward-biased at 200 mV, a current of 75 μA is obtained. Find the magnitude of diffusion current when the diode is (a) unbiased, (b) reverse-biased at 200 mV and (c) forward-biased at 200 mV.

Let ΔE denote the energy gap between the valence band and the conduction band. Th e population of conduction electrons (and of the holes) is roughly proportional to \( \rm e^{\frac{- \triangle E}{2kT}} \). Find the ratio of the concentration of conduction electrons in diamond to that in silicon at room temperature 300 K. ΔE for silicon is 1.1 eV and for diamond is 6.0 eV. How many conduction electrons are likely to be in one cubic metre of diamond ?

The conductivity of a pure semiconductor is roughly proportional to \( \rm e^{\frac{- \triangle E}{2kT}} \) where ΔE is the band gap. The band gap for germanium is 0.74 eV at 4 K and 0.67 eV at 300 K. By what factor does the conductivity of pure germanium increase as the temperature is raised from 4 K to 300 K ?

Estimate the proportion of boron impurity which will increase the conductivity of a pure silicon sample by a factor of 100. Assume that each boron atom creates a hole and the concentration of holes in pure silicon at the same temperature is \( \rm 7 \times 10 ^{15} \) holes per cubic metre. Density of silicon is \( \rm 5 \times 10 ^{28} \) atoms per cubic metre.

The product of the hole concentration and the conduction electron concentration turns out to be independent of the amount of any impurity doped. The concentration of conduction electrons in germanium is \( \rm 6 \times 10 ^{19} \) per cubic metre. When some phosphorus impurity is doped into a germanium sample, the concentration of conduction electrons increases to \( \rm 2 \times 10 ^{23} \) per cubic metre. Find the concentration of the holes in the doped germanium.

The conductivity of an intrinsic semiconductor depends on temperature as \( \rm \sigma = \sigma_{0} e^{\frac{- \triangle E}{2kT}} \), where \( \rm \sigma_{0} \) is a constant. Find the temperature at which the conductivity of an intrinsic germanium semiconductor will be double of its value at T = 300 K. Assume that the gap for germanium is 0.650 eV and remains constant as the temperature is increased.

A semiconducting material has a band gap of 1 eV. Acceptor impurities are doped into it which create acceptor levels 1 meV above the valence band. Assume that the transition from one energy level to the other is almost forbidden if kT is less than 1/50 of the energy gap. Also, if kT is more than twice the gap, the upper levels have maximum population. The temperature of the semiconductor is increased from 0 K. The concentration of the holes increases with temperature and after a certain temperature, it becomes approximately constant. As the temperature is further increased, the hole concentration again starts increasing at a certain temperature. Find the order of the temperature range in which the hole concentration remains approximately constant.

Calculate the number of states per cubic metre of sodiumin 3s band. The density of sodium is \( \rm 10^{13} kgm^{-3} \). How many of them are empty ?

In a pure semiconductor, the number of conduction electrons is \( \rm 6 \times 10 ^{19} \) per cubic metre. How many holes are there in a sample of size 1 cm × 1 cm × 1 mm ?

Indium antimonide has a band gap of 0.23 eV between the valence and the conduction band. Find the temperature at which kT equals the band gap.

The band gap for silicon is 1.1 eV. (a) Find the ratio of the band gap to kT for silicon at room temperature 300 K. (b) At what temperature does this ratio become one tenth of the value at 300 K ? (Silicon will not retainits structure at these high temperatures.)

When a semiconducting material is doped with an impurity, new acceptor levels are created. In a particular thermal collision, a valence electron receives an energy equal to 2 kT and just reaches one of the acceptor levels. Assuming that the energy of the electron was at the top edge of the valence band and that the temperature T is equal to 300 K, find the energy of the acceptor levels above the valence band.

The band gap between the valence and the conduction bands in zinc oxide (ZnO) is 3.2 eV. Suppose an electron in the conduction band combines with a hole in the valence band and the excess energy is released in the form of electromagnetic radiation. Find the maximum wavelength that can be emitted in this process.

Suppose the energy liberated in the recombination of a hole–electron pair is converted into electromagnetic radiation. If the maximum wavelength emitted is 820 nm, what is the band gap ?

Find the maximum wavelength of electromagnetic radiation which can create a hole–electron pair in germanium. The band gap in germanium is 0.65 eV.

In a photodiode, the conductivity increases when the material is exposed to light. It is found that the conductivity changes only if the wavelength is less than 620 nm. What is the band gap ?

Let ΔE denote the energy gap between the valence band and the conduction band. Th e population of conduction electrons (and of the holes) is roughly proportional to \( \rm e^{\frac{- \triangle E}{2kT}} \). Find the ratio of the concentration of conduction electrons in diamond to that in silicon at room temperature 300 K. ΔE for silicon is 1.1 eV and for diamond is 6.0 eV. How many conduction electrons are likely to be in one cubic metre of diamond ?

Let X = \( \rm A \overline{BC} + B \overline{CA} + C \overline{AB} \). Evaluate X for (a) A = 1, B = 0, C = 1 (b) A = B = C = 1, and (c) A = B = C = 0.

Design a logical circuit using AND, OR, and NOT gates to evaluate \( \rm A \overline{BC} + B \overline{CA} \).

Show that \( \rm AB + \overline{AB} \) is always 1.

Why is an NPN transistor preferred over a PNP transistor?

What path does the electron follow in the electric field when the electron is projected normally in the field?

An electron passes through a space without deviation. Does it mean, there is no electric or magnetic field?

Is there any condition that an electron does not experience any force inside a magnetic field?

Are the specific charges of an electron and proton the same? Explain.

Oil has a density of 800 kgm^-3. A 1 $\rm\mu m$ diameter oil droplet acquires 10 extra electrons as sprayed. What potential difference between two parallel plates 1 cm apart will cause the droplet to be suspended in the air?

In a p-n junction, the depletion region is 400 nm wide and an electric field of \( \rm 5 \times 10 ^{5} Vm^{-1} \) exists in it. (a) Find the height of the potential barrier. (b) What should be the minimum kinetic energy of a conduction electron which can diffuse from the n-side to the p-side ?

The current–voltage characteristic of an ideal p-njunction diode is given by \[ \rm i = i_{0} ( e^{\frac{eV}{kT}} - 1 ) \] where the drift current \( \rm i_{0} \) equals 10 μA. Take the temperature T to be 300 K. (a) Find the voltage \( \rm V_{0} \) for which \( \rm e^{\frac{eV}{kT}} \) = 100. One can neglect the term 1 for voltages greater than this value. (b) Find an expression for the dynamic resistance of the diode as a function of V for \( \rm V > V_{0} \). (c) Find the voltage for which the dynamic resistance is 0.2 Ω.

Consider a p-n junction diode having the characteristic \[ \rm i = i_{0} ( e^{\frac{eV}{kT}} - 1 ) \] where \( \rm i_{0} \) = 20 μA. The diode is operated at T = 300 K. (a) Find the current through the diode when a voltage of 300 mV is applied across it in forward bias. (b) At what voltage does the current double?

When the base current in a transistor is changed from 30 μA to 80 μA, the collector current is changed from 1.0 mA to 3.5 mA. Find the current gain β.

A load resistor of 2 k Ω is connected in the collector branch of an amplifier circuit using a transistor in common-emitter mode. The current gain β = 50. The input resistance of the transistor is 0.50 kΩ. If the input current is changed by 50 μA, (a) by what amount does the output voltage change, (b) by what amount does the input voltage change and (c) what is the power gain?

Calculate the number of states per cubic metre of sodiumin 3s band. The density of sodium is \( \rm 10^{13} kgm^{-3} \). How many of them are empty ?

In a pure semiconductor, the number of conduction electrons is \( \rm 6 \times 10 ^{19} \) per cubic metre. How many holes are there in a sample of size 1 cm × 1 cm × 1 mm ?

Indium antimonide has a band gap of 0.23 eV between the valence and the conduction band. Find the temperature at which kT equals the band gap.

The band gap for silicon is 1.1 eV. (a) Find the ratio of the band gap to kT for silicon at room temperature 300 K. (b) At what temperature does this ratio become one tenth of the value at 300 K ? (Silicon will not retainits structure at these high temperatures.)

When a semiconducting material is doped with an impurity, new acceptor levels are created. In a particular thermal collision, a valence electron receives an energy equal to 2 kT and just reaches one of the acceptor levels. Assuming that the energy of the electron was at the top edge of the valence band and that the temperature T is equal to 300 K, find the energy of the acceptor levels above the valence band.

The band gap between the valence and the conduction bands in zinc oxide (ZnO) is 3.2 eV. Suppose an electron in the conduction band combines with a hole in the valence band and the excess energy is released in the form of electromagnetic radiation. Find the maximum wavelength that can be emitted in this process.

Suppose the energy liberated in the recombination of a hole–electron pair is converted into electromagnetic radiation. If the maximum wavelength emitted is 820 nm, what is the band gap ?

Find the maximum wavelength of electromagnetic radiation which can create a hole–electron pair in germanium. The band gap in germanium is 0.65 eV.

In a photodiode, the conductivity increases when the material is exposed to light. It is found that the conductivity changes only if the wavelength is less than 620 nm. What is the band gap ?

Let ΔE denote the energy gap between the valence band and the conduction band. Th e population of conduction electrons (and of the holes) is roughly proportional to \( \rm e^{\frac{- \triangle E}{2kT}} \). Find the ratio of the concentration of conduction electrons in diamond to that in silicon at room temperature 300 K. ΔE for silicon is 1.1 eV and for diamond is 6.0 eV. How many conduction electrons are likely to be in one cubic metre of diamond ?

The conductivity of a pure semiconductor is roughly proportional to \( \rm T^{\frac{3}{2}} e^{\frac{- \triangle E}{2kT}} \) where ΔE is the band gap. The band gap for germanium is 0.74 eV at 4 K and 0.67 eV at 300 K. By what factor does the conductivity of pure germanium increase as the temperature is raised from 4 K to 300 K ?

Estimate the proportion of boron impurity which will increase the conductivity of a pure silicon sample by a factor of 100. Assume that each boron atom creates a hole and the concentration of holes in pure silicon at the same temperature is \( \rm 7 \times 10 ^{15} \) holes per cubic metre. Density of silicon is \( \rm 5 \times 10 ^{28} \) atoms per cubic metre.

The product of the hole concentration and the conduction electron concentration turns out to be independent of the amount of any impurity doped. The concentration of conduction electrons in germanium is \( \rm 6 \times 10 ^{19} \) per cubic metre. When some phosphorus impurity is doped into a germanium sample, the concentration of conduction electrons increases to \( \rm 2 \times 10 ^{23} \) per cubic metre. Find the concentration of the holes in the doped germanium.

The conductivity of an intrinsic semiconductor depends on temperature as \( \rm \sigma = \sigma_{0} e^{\frac{- \triangle E}{2kT}} \), where \( \rm \sigma_{0} \) is a constant. Find the temperature at which the conductivity of an intrinsic germanium semiconductor will be double of its value at T = 300 K. Assume that the gap for germanium is 0.650 eV and remains constant as the temperature is increased.

A semiconducting material has a band gap of 1 eV.Acceptor impurities are doped into it which create acceptor levels 1 meV above the valence band. Assume that the transition from one energy level to the other is almost forbidden if kT is less than 1/50 of the energy gap. Also, if kT is more than twice the gap, the upper levels have maximum population. The temperature of the semiconductor is increased from 0 K. Theconcentration of the holes increases with temperature and after a certain temperature it becomes approximately constant. As the temperature is further increased, the hole concentration again starts increasing at a certain temperature. Find the order of the temperature range in which the hole concentration remains approximately constant.

In a p-n junction, the depletion region is 400 nm wide and an electric field of \( \rm 5 \times 10 ^{5} Vm^{-1} \) exists in it. (a) Find the height of the potential barrier. (b) What should be the minimum kinetic energy of a conduction electron which can diffuse from the n-side to the p-side ?

The potential barrier existing across an unbiased p-n junction is 0.2 volt. What minimum kinetic energy a hole should have to diffuse from the p-side to the n-side if (a) the junction is unbiased, (b) the junction is forward-biased at 0.1 volt and (c) the junction is reverse-biased at 0.1 volt ?

In a p-n junction, a potential barrier of 250 meV exists across the junction. A hole with a kinetic energy of 300 meV approaches the junction. Find the kinetic energy of the hole when it crosses the junction if the hole approached the junction (a) from the p-side and (b) from the n-side.

When a p-n junction is reverse-biased, the current becomes almost constant at 25 μA. When it is forward-biased at 200 mV, a current of 75 μA is obtained. Find the magnitude of diffusion current when the diode is (a) unbiased, (b) reverse-biased at 200 mV and (c) forward-biased at 200 mV.

Let ΔE denote the energy gap between the valence band and the conduction band. Th e population of conduction electrons (and of the holes) is roughly proportional to \( \rm e^{\frac{- \triangle E}{2kT}} \). Find the ratio of the concentration of conduction electrons in diamond to that in silicon at room temperature 300 K. ΔE for silicon is 1.1 eV and for diamond is 6.0 eV. How many conduction electrons are likely to be in one cubic metre of diamond ?

The conductivity of a pure semiconductor is roughly proportional to \( \rm e^{\frac{- \triangle E}{2kT}} \) where ΔE is the band gap. The band gap for germanium is 0.74 eV at 4 K and 0.67 eV at 300 K. By what factor does the conductivity of pure germanium increase as the temperature is raised from 4 K to 300 K ?

Estimate the proportion of boron impurity which will increase the conductivity of a pure silicon sample by a factor of 100. Assume that each boron atom creates a hole and the concentration of holes in pure silicon at the same temperature is \( \rm 7 \times 10 ^{15} \) holes per cubic metre. Density of silicon is \( \rm 5 \times 10 ^{28} \) atoms per cubic metre.

The product of the hole concentration and the conduction electron concentration turns out to be independent of the amount of any impurity doped. The concentration of conduction electrons in germanium is \( \rm 6 \times 10 ^{19} \) per cubic metre. When some phosphorus impurity is doped into a germanium sample, the concentration of conduction electrons increases to \( \rm 2 \times 10 ^{23} \) per cubic metre. Find the concentration of the holes in the doped germanium.

The conductivity of an intrinsic semiconductor depends on temperature as \( \rm \sigma = \sigma_{0} e^{\frac{- \triangle E}{2kT}} \), where \( \rm \sigma_{0} \) is a constant. Find the temperature at which the conductivity of an intrinsic germanium semiconductor will be double of its value at T = 300 K. Assume that the gap for germanium is 0.650 eV and remains constant as the temperature is increased.

A semiconducting material has a band gap of 1 eV. Acceptor impurities are doped into it which create acceptor levels 1 meV above the valence band. Assume that the transition from one energy level to the other is almost forbidden if kT is less than 1/50 of the energy gap. Also, if kT is more than twice the gap, the upper levels have maximum population. The temperature of the semiconductor is increased from 0 K. The concentration of the holes increases with temperature and after a certain temperature, it becomes approximately constant. As the temperature is further increased, the hole concentration again starts increasing at a certain temperature. Find the order of the temperature range in which the hole concentration remains approximately constant.

Calculate the number of states per cubic metre of sodiumin 3s band. The density of sodium is \( \rm 10^{13} kgm^{-3} \). How many of them are empty ?

In a pure semiconductor, the number of conduction electrons is \( \rm 6 \times 10 ^{19} \) per cubic metre. How many holes are there in a sample of size 1 cm × 1 cm × 1 mm ?

Indium antimonide has a band gap of 0.23 eV between the valence and the conduction band. Find the temperature at which kT equals the band gap.

The band gap for silicon is 1.1 eV. (a) Find the ratio of the band gap to kT for silicon at room temperature 300 K. (b) At what temperature does this ratio become one tenth of the value at 300 K ? (Silicon will not retainits structure at these high temperatures.)

When a semiconducting material is doped with an impurity, new acceptor levels are created. In a particular thermal collision, a valence electron receives an energy equal to 2 kT and just reaches one of the acceptor levels. Assuming that the energy of the electron was at the top edge of the valence band and that the temperature T is equal to 300 K, find the energy of the acceptor levels above the valence band.

The band gap between the valence and the conduction bands in zinc oxide (ZnO) is 3.2 eV. Suppose an electron in the conduction band combines with a hole in the valence band and the excess energy is released in the form of electromagnetic radiation. Find the maximum wavelength that can be emitted in this process.

Suppose the energy liberated in the recombination of a hole–electron pair is converted into electromagnetic radiation. If the maximum wavelength emitted is 820 nm, what is the band gap ?

Find the maximum wavelength of electromagnetic radiation which can create a hole–electron pair in germanium. The band gap in germanium is 0.65 eV.

In a photodiode, the conductivity increases when the material is exposed to light. It is found that the conductivity changes only if the wavelength is less than 620 nm. What is the band gap ?

Let ΔE denote the energy gap between the valence band and the conduction band. Th e population of conduction electrons (and of the holes) is roughly proportional to \( \rm e^{\frac{- \triangle E}{2kT}} \). Find the ratio of the concentration of conduction electrons in diamond to that in silicon at room temperature 300 K. ΔE for silicon is 1.1 eV and for diamond is 6.0 eV. How many conduction electrons are likely to be in one cubic metre of diamond ?

Let X = \( \rm A \overline{BC} + B \overline{CA} + C \overline{AB} \). Evaluate X for (a) A = 1, B = 0, C = 1 (b) A = B = C = 1, and (c) A = B = C = 0.

Design a logical circuit using AND, OR, and NOT gates to evaluate \( \rm A \overline{BC} + B \overline{CA} \).

Show that \( \rm AB + \overline{AB} \) is always 1.

Why is an NPN transistor preferred over a PNP transistor?