Question 1

Marks: 1

Two identical resistors R are connected in parallel to an ac power supply with root mean squared (rms) voltage which provides rms current, I. What is the maximum power developed in one of the resistors in the circuit?

$\frac{I V}{\sqrt{2}}$
$I V$
$\sqrt{2} I V$
$2 I V$

Key Concepts

Root-Mean-Square Current & Voltage

Question 2

Marks: 1

A square loop of conducting wire is rotated at a constant rate in a region of magnetic field. The graph shows the variation with time t of the induced emf in the loop during one cycle.

11-2-hl-mcq-medium-12-qun

The resistance of the coil is 10.0 Ω. Which of the following values gives the average power dissipated in the loop?

$90$ W
45 W
$\frac{90}{\sqrt{2}}$ W
$90 \sqrt{2}$ W

Key Concepts

Average Power Calculations

Question 3

Marks: 1

What is the maximum instantaneous power delivered by a sinusoidal ac power supply with rms voltage V supplying rms current 2I?

$I V$
$2 I V$
$4 I V$
$\frac{2}{\sqrt{2}} I V$

Key Concepts

Root-Mean-Square Current & Voltage

Question 4

Marks: 1

An ac generator produces a root mean squared emf ε at frequency f. The rotational speed of the coil in the generator is increased by a factor of three. Which of the following correctly identifies the new values of frequency and output emf_rms?

	emf	frequency
A.	$3 ε$	$\frac{f}{3}$
B.	$3 ε$	$3 f$
C.	$3 \sqrt{2} ε$	$3 f$
D.	$3 \sqrt{2} ε$	$\frac{f}{3}$

Key Concepts

Root-Mean-Square Current & Voltage

Question 5

Marks: 1

An ideal transformer is supplied with power P. The transformer has N_p turns on the primary coil and N_s turns on the secondary coil. Select the correct power output from the secondary coil.

$\frac{N_{p} V_{s} I_{p}}{N_{s}}$
$\frac{N_{p}}{N_{s}} \times P$
$P$
$P^{- 1}$

Key Concepts

Transformer Calculations

Question 6

Marks: 1

The graph shows the variation with time t of the output voltage V of an ac generator.

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Which graph, with identical scales on the axes, shows the output when the speed of rotation is doubled?

Key Concepts

AC Generators

Question 7

Marks: 1

A power station produces ac voltage which is stepped up by a factor of 10⁴. This reduces the power loss in the transmission cables by a factor of

10²
10⁴
10⁸
10¹²

Key Concepts

AC Electrical Power Distribution

Question 8

Marks: 1

The secondary coil of an ac transformer is connected to two diodes as shown.

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Which graph correctly shows the variation with time of the potential difference V_PQ between P and Q?

Key Concepts

Diode Bridges
Rectification

Question 9

Marks: 1

A resistor of 3.0 kΩ is connected to an alternating current (ac) power supply of root mean square voltage 120 V. The graph shows the power dissipated in the resistor.

11-2-hl-mcq-medium-q9-graph