Here are the solutions to the multiple-choice questions:
9. At resonance the phase angle equals
- At resonance in an RLC circuit, the inductive reactance (XL) cancels out the capacitive reactance (XC). The circuit behaves purely resistively.
- Therefore, the voltage and current are in phase, and the phase angle (ϕ) is 0∘.
- Answer: a) 0Degree
10. The band width of resonant circuit is
- The bandwidth (Δf) of a resonant circuit is inversely proportional to its quality factor (Q). The formula is Δf=Qfr, where fr is the resonant frequency.
- Answer: b) InverselyproportionaltoQ
11. In silicon atom distribution of electrons in cells is
- Silicon (Si) has an atomic number of 14. Its electron configuration is 1s22s22p63s23p2.
- The electron distribution in shells (K, L, M) is:
- K-shell (1st shell): 2 electrons
- L-shell (2nd shell): 2+6=8 electrons
- M-shell (3rd shell): 2+2=4 electrons
- So the distribution is 2, 8, 4.
- Answer: a) 2,8,4
12. An inductive circuit with L=100mH and R=10KΩ has time constant of
- The time constant (τ) for an RL circuit is given by the formula τ=RL.
- Given L=100mH=100×10−3H=0.1 H.
- Given R=10KΩ=10×103Ω.
- τ=10×103Ω0.1H=100000.1s=0.00001s
- τ=10×10−6s=10µs
- Answer: d) 10µsec
13. A capacitive circuit with R=15KΩ and C=0.01µF has a time constant of
- The time constant (τ) for an RC circuit is given by the formula τ=RC.
- Given R=15KΩ=15×103Ω.
- Given C=0.01µF=0.01×10−6F=1×10−8 F.
- τ=(15×103Ω)×(1×10−8F)
- τ=15×10−5s=0.00015s
- τ=150×10−6s=150µs
- Answer: c) 150µsec
14. The development of voltage difference due to light intensity on the surface of a PN junction is known
- When light falls on a PN junction, it generates electron-hole pairs, leading to a voltage difference across the junction. This phenomenon is called the photovoltaic effect and is the basis for solar cells.
- Answer: b) Photovoltaiceffect
15. The function of choke in fluorescent tube is
- A choke (inductor) in a fluorescent tube circuit performs two main functions:
- It provides a high voltage spike (strike voltage) to ionize the gas and start the discharge when the circuit is switched on.
- Once the tube is lit, it limits the current flowing through the tube to a safe operating level.
- Answer: c) Bothaandbarecorrect
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