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Physics [2 Mark Question Answer]

Electrical Power and Household Circuits · ICSE STD 10 (ICSE - English Medium). 15 questions.

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[2 Mark Question Answer]

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15 questions · timed · auto-graded

Question 12 Marks
How does the (i) thickness and (ii) length of a fuse wire depend on its current rating
Answer

The current rating of the fuse wire

(i) Is directly proportional to the thickness of the fuse wire. Thicker the fuse wire, higher will be the current rating of the fuse wire.

(ii) The current rating of the fuse wire does not depend on its length.

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Question 22 Marks

In following Figure shows two bulbs with switches and fuse connected to mains through a socket.
label each component

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Question 32 Marks
The following diagram shows three lamps and three switches 1, 2 and 3
(a) Name the switch / switches to be closed so as to light all the three lamps.
(b) How are the lamps connected: in series or in parallel?

Answer
(a) Switches 2 and 3.
(b) The lamps are connected in series.
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Question 42 Marks
Why is it necessary to have an earth wire installed in a power circuit, but not in a lighting circuit?
Answer
Power circuit carries high power and costly devices. If there is some unwanted power signal (noise) in the wire it can damage the device. To reduce this effect earth is necessary.
Lighting circuit carries low power (current). So, we ignore the earth terminal.
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Question 52 Marks
Name the colour code of the wire which is connected to (i) metallic body of an appliance, (ii) switch for the appliance.
Answer

Colour code of the wire which is connected to

(i) The metallic body of an appliance is the green coloured, earthing wire.

(ii) The switch of the appliance is the red coloured, live wire.

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Question 62 Marks
For earthing an electrical appliance, one has to remove the paint from the metal body of the appliance where the electrical contact is made. Explain the reason.
Answer
The paint provides an insulating layer on the metal body of the appliance. To make earth connection therefore, the paint must be removed from the body part where connection is to be made.
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Question 72 Marks
A switch is not touched with wet hands while putting it on or off. Give a reason for your answer.
Answer
A switch should not be touched with wet hands. If water reaches the live wire, it forms a conducting layer between the hand and the live wire of the switch through which the current passes to the hand and the person may get a fatal shock.
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Question 82 Marks
An electric kettle is rated 3 kW, 250 V. give reason whether this kettle can be used in a circuit
which contains a 13 A fuse.
Answer
Yes, this kettle can be used in a circuit which contains a $13 A$ fuse because safe limit of current for kettle is,
$I =\frac{3000 W }{250 V }=12 A$
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Question 92 Marks
‘A fuse is rated 8 A’. can it be used with an electrical appliance of rating 5kW, 200V?
Answer
The safe limit of current which can flow through the electrical appliance is I = P/V = 5000/200
= 25 A; which is greater than 8 A. So, such fuse cannot be used.
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Question 102 Marks
State the function of the following in a house circuiting of main switch.
Answer
Main switch is connected in the live and neutral wires. It is used to cut the connections of the live as well as the neutral wires simultaneously from the main supply.
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Question 112 Marks
State the function of the following in a house circuiting
kWh meter .
Answer
After the company fuse, the cable is connected to a kWh meter and from this meter; connections are made to the distribution board through a main fuse and a main switch.
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Question 122 Marks
What is the pole fuse? Write down its current rating.
Answer
Before the electric line is connected to the meter in a house, a fuse of rating (≈ 50 A) is connected in the live wire at the pole or just before the meter. This fuse is called the pole fuse. Its current rating is ≈ 50 A
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Question 132 Marks
Name the device used to (a) increase the voltage at the generating station (b) decrease the voltage at the substation for its supply.
Answer
(a) Step-up transformer
(b) Step-down transformer
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Question 142 Marks
How should the electric lamps be connected with the mains so that the switching on or off a lamp has no effect on other lamps?
Answer
All the electrical appliances in a building should be connected in parallel at the mains, each with a separate switch and a separate fuse connected in the live wire so that the switching on or off in a room has no effect on other lamps in the same building.
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Question 152 Marks
Draw a labelled diagram with necessary switch, regulator, etc. to connect a bulb and a fan with the mains. In what arrangement are they connected to the mains : series or parallel?
Answer


These appliances are connected to the mains in a parallel arrangement.
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[2 Mark Question Answer] - Physics STD 10 Questions - Vidyadip