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10
MCQ (Multiple Correct Answer)

Electrical energy is transmitted over large distances at high alternating voltages. Which of the following statements is (are) correct?

A
For a given power level, there is a lower current
B
Lower current implies less power loss
C
Transmission lines can be made thinner
D
It is easy to reduce the voltage at the receiving end using step-down transformers
11
MCQ (Multiple Correct Answer)

For a $L-C-R$ circuit, the power transferred from the driving source to the driven oscillator is $P=I^2 Z \cos \phi$.

A
Here, the power factor $\cos \phi \geq 0, P \geq 0$
B
The driving force can give no energy to the oscillator $(P=0)$ in some cases
C
The driving force cannot syphon out $(P<0)$ the energy out of oscillator
D
The driving force can take away energy out of the oscillator
12
MCQ (Multiple Correct Answer)

When an $A C$ voltage of 220 V is applied to the capacitor $C$

A
the maximum voltage between plates is 220 V
B
the current is in phase with the applied voltage
C
the charge on the plates is in phase with the applied voltage
D
power delivered to the capacitor is zero
13
MCQ (Multiple Correct Answer)

The line that draws power supply to your house from street has

A
zero average current
B
220 V average voltage
C
voltage and current out of phase by $90 \Upsilon$
D
voltage and current possibly differing in phase $\phi$ such that $|\phi|<\frac{\pi}{2}$
14
Subjective

If a L-C circuit is considered analogous to a harmonically oscillating springblock system, which energy of the L-C circuit would be analogous to potential energy and which one analogous to kinetic energy?

Explanation

If we consider a L-C circuit analogous to a harmonically oscillating springblock system. The electrostatic energy $\frac{1}{2} C V^2$ is analogous to potential energy and energy associated with moving charges (current) that is magnetic energy $\left(\frac{1}{2} L I^2\right)$ is analogous to kinetic energy.

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