# Victoria Secondary Prelim 2021 P1

## Quiz by Jessica Lew

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20 questions
• Q1

The diagram shows a wire in the magnetic field between two poles of a magnet. The current in the wire repeatedly changes as shown on the graph. What is the effect on the wire?

The force on the wire alternates between one direction and the opposite direction.

The force on the wire is constant in size and direction

There is no force acting on the wire at any time

There is only a force on the wire when the current reverses

120s
• Q2

The diagram shows part of a magnetic relay. P is part of the core of the electromagnet. Q is part of an armature that is attracted to the core when a current flows through the coil. R is a stud that stops the armature from being attracted too strongly to P.  Which row gives the most suitable materials for P, Q and R?

P(copper) Q( copper) R( iron)

P(copper) Q( copper) R( copper)

P(iron) Q( iron) R( copper)

P(iron) Q( iron) R( iron)

120s
• Q3

Two soft-iron pins are suspended from the North pole of a bar magnet. Which diagram shows how the pins are deflected?

120s
• Q4

Some electrical equipment is connected to a 240 V supply. It is kept inside a metal case which is not earthed. A strand of wire has become loose and touches the metal case as shown. Which statement about this situation is correct?

A fuse in the live wire will blow

The metal case is at 0 V.

An electric current is passing through the metal case.

Someone touching the case would receive an electric shock

120s
• Q5

A mains circuit can safely supply a current of 40 A.A hair-dryer takes 2 A. It is connected to the circuit by a wire which can carry up to 5 A. Which of these fuses would be best to use in the plug fitted to the hair-dryer wire?

1 A

6 A

50 A

3 A

120s
• Q6

A machine that can produce cryptocurrencies such as Bitcoin is rated at 3000 W. Electrical energy costs 20 cents per unit. What is the electrical cost of running 1000 identical machines for 24 hours?

\$600

\$2500

\$6200

\$14400

120s
• Q7

Two copper wires X and Y have the same volume. Wire Y is four times as long as wire X. What is the value of [resistance of wire Y /resistance of wire X ]?

4

64

8

16

120s
• Q8

Which diagram correctly shows the electric field between a positively charged metal sphere and an earthed metal plate?

120s
• Q9

A dolphin has a range of audible frequencies of 150 Hz to 150 kHz. Which range of frequencies can both humans and dolphins hear?

20 Hz to 150 kHz

20 Hz to 150 Hz

20 kHz to150 kHz

150 Hz to 20 kHz

120s
• Q10

Which statement about a converging lens is not correct?

The principal focus of the lens is a point on the principal axis.

All rays of light refracted by the lens pass through the principal focus.

The distance between the centre of the lens and the principal focus is the focal length.

A ray parallel to the principal axis of the lens is refracted through the principal focus

120s
• Q11

A ray of light passes through plastic to air at the angles shown. What is the refractive index of the plastic?

1.61

1.41

1.51

1.25

120s
• Q12

700 g of alcohol at – 25 °C and 500 g of water at 25 °C poured into an insulated container and mixed together. The specific heat capacities of alcohol and water are 2400 J kg-1 K-1 and 4200 J kg-1 K-1 respectively. You may assume negligible heat transfer to the container. What is the temperature of the mixture at thermal equilibrium?

25 °C

3.8 °C

2.8 °C

– 4.2 °C

120s
• Q13

Heat is supplied at the same rate to a solid copper block and molten copper of the same mass in identical containers. Why does the temperature of the solid copper block rise at a slower rate?

The specific heat capacity of solid copper is higher than molten copper.

There is additional latent heat of fusion when changing from solid to molten copper

Solid copper is denser than molten copper.

The conductivity of heat by solid copper is not as good as the molten copper.

120s
• Q14

A thermocouple is set up with the cold junction in melting ice at 0 °C and the hot junction is placed in boiling water at 100 °C. The reading from the sensitive voltmeter is 14 mV. When the hot junction is placed in a container of liquid of unknown temperature while the cold junction remains in the melting ice at 0 °C, the reading of the sensitive voltmeter is – 9 mV. What is the temperature of the container of liquid?

– 64 °C

64 °C

156 °C

– 36 °C

120s
• Q15

Which of the physical properties cannot be used to design a thermometer?

pressure

electrical resistance

mass

volume

120s

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