Transistor: Working

Q.

How do you know if a transistor is NPN or PNP?

Q. Low resistance is present at the base emitter junction of a transistor.

1. True
2. False

Q.

In a common-base mode of a transistor, the collector current is $5.488mA$ for an emitter current of $5.60mA$. The value of the base current amplification factor ($\beta$) will be

1. $47$

2. $49$

3. $51$

4. $48$

Q. An electron emitted by a heated cathode and accelerated through a potential difference of $2\text{kV}$ enters a region with uniform magnetic field of $0.15\text{T}$. If the magnetic field makes an angle of ${30}^{\circ }$ with the initial velocity, the radius of the hellical trajectory of electron will be: $(m_e=9.0\times {10}^{-31}\text{kg})$

1. $1.5\text{mm}$
2. $1\text{mm}$
3. $0.5\text{mm}$
4. $2.5\text{mm}$

Q.

In a common base amplifier, the phase difference between the input signal voltage and output voltage is

1. $\frac{\pi }{2}$

2. $0$

3. $\pi$

4. $\frac{\pi }{4}$

Q.

What happens when use a transistor as an amplifier?

Q. The diagram shows the biasing of an n-p-n transistor in common emitter configuration used in an amplifier. The design of the transistor is such that $98\%$ of the charge carriers from emitter reach the collector. If base current changes from $50\mu A$ to $100\mu A$, then the corresponding change in the voltage across the load resistance $R_L$ will be

1. $0.25V$
2. $0.25V$
3. $24.5V$
4. $49.0V$

Q.

A NPN transistor conducts when

1. Both collector and emitter are positive with respect to the base
2. Collector is positive and emitter is negative with respect to the base
3. Collector is positive and emitter is at same potential as the base
4. Both collector and emitter are negative with respect to the base

Q. In a common emitter transistor circuit, the base current is $40\mu A$, then $V_{BE}$ is :-

1. $2\text{V}$
2. $0.2\text{V}$
3. $0.8\text{V}$
4. Zero

Q.

In an NPN transistor circuit, the collector current is 10 mA. If 90% of the electrons emitted reach the collector, the emitter current (i_E) and base current (i_B) are given by

1. 

2. 

3. 

4.