This document consists of 6 printed pages.

20 M

[Total 5]

Test (Unit 21-22) :................................................................................................................

:........................................................ Code: 5054 Class: CII

urn over[T

heory Section:

T [Total arks]

Time Allowed: 35Minutes

Maximum Marks: 25

NIQUE SCIENCE ACADEMY U

Date

Name

Paper: Physics

1

Dedicated to My Son Mohammad Irtaza Zain. Code 5054

On Fig. 1.1, use an arrow to show the direction of the conventional current in the coil. [1]

Fig. 1.1

Fig. 1.1 shows a simple motor with a rectangular coil that is free to rotate about an axis A1 1A2. The coil is connected to a battery by brushes B1 and B2.

N

+ –

S

B2B1

A2

A1

(a) Brush B1 is connected to the positive terminal of the battery and brush B2 is connected to the negative terminal of the battery.

(i)

(ii) State the direction in which the coil rotates, when viewed from the end closest to the brushes.

.......................................................................................................................................[1]

(b) State what difference, if any, each of the following changes makes to the rotation of the coil:

(i) using a battery with a larger potential difference,

...........................................................................................................................................

(ii) using a coil with several turns of wire carrying the same current as in (a),

...........................................................................................................................................

(iii) using a stronger magnetic field.

...........................................................................................................................................[3]Irt

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[Total 8]

[6]

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Fig. 2.1

In the laboratory demonstration shown in Fig. 2.1, a copper rod rolls at a steady speed down 2 the sloping parallel copper rails. The rails are in the region of a strong magnetic field that acts vertically downwards.

parallel copper railssloping downwards in direction of arrow

copper rod

connecting wiresdirection

ofmagnetic

field

very sensitivecentre-zerovoltmeter

V

(a) Explain why the voltmeter shows a deflection.

...................................................................................................................................................

...................................................................................................................................................

...................................................................................................................................................

.............................................................................................................................................. [2]

(b) State, with reasons, the effect on the voltmeter deflection of the following changes:

(i) increasing the strength of the magnetic field,

deflection ...........................................................................................................................

reason ...............................................................................................................................

...........................................................................................................................................

...........................................................................................................................................

(ii) slightly increasing the slope of the copper rails,

deflection ...........................................................................................................................

reason ...............................................................................................................................

...........................................................................................................................................

...........................................................................................................................................

(iii) changing the direction of the magnetic field so it is parallel to the copper rails and directed down the slope.

deflection ...........................................................................................................................

reason ...............................................................................................................................

...........................................................................................................................................

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Fig. 3.2

Fig. 3.2 shows a transformer. P is the primary coil. S is the secondary coil. The coils are

possible changes to the system in Fig. 3.1 that would increase the induced Fig. 3.1

In Fig. 3.1, a magnet is moving towards one end of a solenoid connected to a sensitive centre-3 (a) zero meter. During this movement a current is induced in the solenoid.

S N

Suggest threecurrent.

1. ...............................................................................................................................................

2. ...............................................................................................................................................

3. ...........................................................................................................................................[3]

(b) wound on an iron core.

P S

P has 200 turns and S has 800 turns. The e.m.f. induced across S is 24 V. The current in S is 0.50 A. The transformer operates with 100% efficiency.

Calculate

(i) the voltage of the supply to P,

voltage = ...........................................................[2]

(ii) the current in P.

current = ...........................................................[2]

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Dedicated to My Son Mohammad Irtaza Zain. Code 5054 [Turn over

4

5 MCQ SECTION: [Total Marks] 1 Four nails, A, B, C and D, are tested to find which makes the strongest permanent magnet.

N S

nail

bar magnet

paper clips

One of the nails is placed against a bar magnet and the number of paper clips which the nail can support is recorded. The bar magnet is then removed and the number of paper clips remaining attached to the nail is recorded. Each nail is tested in turn.

Which nail becomes the strongest permanent magnet?

number of paper clips attached to the nail nail

bar magnet present bar magnet removed

A 2 0

B 2 1

C 4 3

D 5 2

The diagram shows an a.c. generator.

N S

coil

output voltage

rotationof coil

With the coil in the position shown, the output voltage is +10V.

When does the output voltage become –10V?

A when the coil has turned 90°

B when the coil has turned 180°

C when the coil has turned 270°

D when the coil has turned 360°Irtaz

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Dedicated to My Son Mohammad Irtaza Zain. Code 5054 [Turn over

5

The diagram shows a simple transformer.

core

outputinput

From which material should the core be made?

A aluminium

B copper

C iron

D steel

The transformer in the diagram has an input coil with Ni turns and an output coil with No turns.

input coils output coils

The output voltage needs to be lower than the input voltage.

What is needed for the transformer to work correctly?

input supply relative values of Ni and No

A a.c. Ni > No

B a.c. Ni < No

C d.c. Ni > No

D d.c. Ni < No

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Dedicated to My Son Mohammad Irtaza Zain. Code 5054

6

Two parallel wires carry currents in the same direction.

Which diagram shows the magnetic field around each wire and the direction of the force on each wire?

A

forces

magneticfields

currents

B

forces

magneticfields

currents

C

forces

magneticfields

currents

D

forces

magneticfields

currents

5 A B C D

4 A B C D

3 A B C D

2 A B C D

1 A B C D

MCQ Answer Sheet

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