Electricity 2

Consider the electric circuit shown in the diagram below.

The reading on the voltmeter $V$ is ...

(A) $0\; V$
(B) $2\; V$
(C) $4\; V$
(D) $6\; V$

Check your answer

B is correct
Two light bulbs $P$ and $Q$ are identical in all respects, except that $P's$ filament is thicker than $Q's.$ If the same potential difference is applied to each, then …

(A) $P$ will burn brighter because it has the greater resistance.
(B) $Q$ will burn brighter because it has the greater resistance.
(C) $P$ will burn brighter because it has the lower resistance.
(D) $Q$ will burn brighter because it has the lower resistance.

Check your answer

C is correct

The ammeter and the battery in the sketch to the right have negligible resistance. The resistors are in parallel. What will happen to the ammeter and voltmeter readings when switch

$S$ is closed?

Diagram of a circuit with a switch, ammeter and two resistors

Answer	Ammeter Reading	Voltmeter Reading
(A)	increases	unchanged
(B)	increases	increases
(C)	decreases	decreases
(D)	decreases	increases

Check your answer

A is correct

In the circuit shown the bulb marked

$2R$ has twice the resistance of the bulb marked

$R.$ Compared with bulb

$2R,$ the current in bulb

$R$ and its brightness compared to the other bulb, is …

Diagram of circuit with two bulbs one with twice as much resistance as the other

Answer	Current in $R$	Brightness in $R$
(A)	larger	brighter
(B)	larger	dimmer
(C)	smaller	brighter
(D)	smaller	dimmer

Check your answer

B is correct

Thabiseng connected four identical light bulbs in a circuit as shown to the right. She observes that the brightness of bulb $A$ varies if some of the switches are closed. In which case will bulb $A$ burn brightest?

(A) $S_1$ closed with $S_2$ and $S_3$ open
(B) $S_1$ and $S_2$ closed with $S_3$ open
(C) $S_1,$ $S_2$ and $S_3$ closed
(D) $S_1,$ $S_2$ and $S_3$ open

Check your answer

C is correct
Two identical light bulbs $X$ and $Y,$ which are rated at $60\; W;$ $240\; V,$ are connected in series to a $240\; V$ source as shown in the diagram below. If point $A$ in the circuit is now connected to point $B$ by a piece of copper wire with very low resistance, how will the brightness of each bulb change?

(A) Both $X$ and $Y$ will burn brighter.
(B) Both $X$ and $Y$ will burn less brightly.
(C) $X$ will burn brighter and $Y$ will not burn.
(D) $Y$ will burn brighter and $X$ will not burn.

Check your answer

D is correct
A battery is connected to a small lamp. If a second identical lamp is connected in series with the first, what will happen to the current provided by the battery?

(A) it will decrease
(B) it will remain the same
(C) it will increase
(D) it will become zero

Check your answer

A is correct
A $200\; V$ electrical outlet is protected by a circuit breaker. The circuit breaker will cut out if the current drawn from the outlets exceeds $16\; A.$ A $1000\; W$ toaster and a $2000\; W$ kettle can be connected to the outlet, either singly, or both in parallel using a double adapter. Which use of the appliances will trip the circuit breaker?

(A) the toaster used on its own
(B) the kettle used on its own
(C) the toaster and the kettle together
(D) none of the above

Check your answer

D is correct
Two light bulbs are marked $230\; V;$ $75\; W$ and $230\; V;$ $150\; W.$ If the first bulb has a resistance $R,$ then the resistance of the second is …

(A) $¼\; R$
(B) $½ \;R$
(C) $2 \;R$
(D) $4\; R$

Check your answer

B is correct
Two resistors of resistance $2R$ and $3R$ are connected in series with a battery, which has an emf of $E$ and an internal resistance $R.$ What is the potential difference across the resistor of resistance $2R$ ?

(A) $E/3$
(B) $2E/5$
(C) $E/2$
(D) $2E$

Check your answer

A is correct