RC - ELEX 2

1. The B-H curve for _____ will be a straight line passing through the origin.

• silicon steel

• soft iron

• hardened steel

• air

2. The amplifier circuit shown below uses a silicon transistor. The capacitors C_C and C_E can be assumed to be short at signal frequency and the effect of output resistance r_0 can be ignored. If C_E is disconnected from the circuit, which one of the following statements is TRUE?

• Both input resistance Ri and the magnitude of voltage gain Av increase

• The input resistance Ri decreases and the magnitude of voltage gain Av decreases

• The input resistance Ri increases and the magnitude of voltage gain Av decreases

• Both input resistance Ri and the magnitude of voltage gain Av decrease

3. When a current source I is suddenly connected across a two terminal relaxed RC circuit at time t = 0, the voltage across the current source is shown in figure. The RC circuit is ______.

• a parallel combination of R and C

• a series combination of R and C

• a pure capacitor

• a series combination of R and parallel combination of R and C

4. All but which one of the following statements regarding extrinsic semiconducting silicon is true?

• Electrons are donated to the conduction band in n-type silicon.

• The Fermi energy is raised by Group V elements in extrinsic silicon

• Group III elements accept electrons from the valence band of silicon.

• The number of n-type carriers equals the number of p-type carriers in extrinsic silicon.

5. In an ac circuit, what can be the maximum and minimum values of power factor?

• 1 and 0

• 2 and 0

• 0 and -1

• 1 and -1

6. For all resistor wattage ratings except 1/8 watt, what is the maximum allowable change in resistance for a 1000-hour rated load life test?

• 10%

• 5%

• 15%

• 12%

7. Si transistor of the following figure has a α = 0.9 and I_CE = 0, V_EE = 5 V and Vcc = 13 V, then R_E will be ____ if I_EQ = 1 mA.

• 4.3 kΩ

• 5 kΩ

• 3 kΩ

• 4 kΩ

8. What is the rms value of the wave shown in the figure?

• about 25 V

• about 95 V

• about 50 V

• about 80 V

9. The 'h' parameters of the circuit shown in the figure are h_ib = 25 Ω, h_fb = 0.999 and h_ob = 10¯⁶ Ω. What is the voltage gain?

• 400

• 100

• 300

• 200

10. If the cross-sectional area of a magnetic field increases, but the flux remains the same, the flux density _______.

• increases

• remains the same

• doubles

• decreases