Electricity Class X

Electricity Class X

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Multiple Choice

Current between two points will not be flowing if

• Both the points have same potential

• Circuit is open

• Potential Difference between the point is zero

• All of them

Multiple Choice

If 'I' is the current through a wire and e is the charge of electron, then the number of electrons in t second will be given by :

• Ie/t

• Ite

• e/It

• It/e

Multiple Choice

All the following statements are correct except :

• A body is said to be positively charged when it has got excess of electrons

• When a body is charged positively, some electron escape from it

• The presence of moisture in the air reduces the conductivity of charge

• None of the above

Multiple Choice

4/25 coulomb of charge contains _________ electrons :

• 10^(15)

• 10^(18)

• 10*(20)

• None of these

Multiple Choice

A wire of resistance R is cut into n equal parts. These parts are then connected in parallel. The equivalent resistance of combination will be :

• nR

• R/n

• n/R

• R/(n^(2))

Multiple Choice

Three resistance each of 8 ohm are connected to a triangle. The resistance between any two terminals :

• 12 ohm

• 2 ohm

• 6 ohm

• 16/3 ohm

Multiple Choice

The filament of an electric bulb is made of tungsten because :

• its resistance is negligible

• it is cheaper

• its melting point is high

• its filament is easily made

Multiple Choice

The smallest resistance that can be obtained from a combination of n identical resistors each of resistance R is :

• R/n

• R/n^2

• nR

• Rn^2

Multiple Choice

Number of joules in 1kWh is :

• 36 X 10^6

• 3.6 x 10^4

• 3.6 x 10^5

• 3.6 x 10^6

Multiple Choice

An electric iron of heating element of resistance 88 ohm is used at 220 volt for 2 hours. The electrical energy spent, in unit, will be :

• 0.8

• 1.1

• 2.2

• 8.8

Multiple Choice

Electrical resistivity of a given metallic wire depends upon :

• its length

• its thickness

• its shape

• nature of material

Multiple Choice

A cylindrical conductor of length l and uniform area of cross section A has resistance R. Another conductor of length 2l and resistance R of the same material has area of cross section :

• A/2

• 3A/2

• 2A

• 3A

Multiple Choice

A student carries out an experiment and plots the V-I graph as shown in the diagram below, of three samples of nichrome wire with resistances R1, R2 and R3 respectively. Which of the following is true?

• R1 = R2 = R3

• R1 > R2 > R3

• R3 > R2 > R1

• R2 > R3 > R1

Multiple Choice

An electric kettle consumes 1 kW of electric power when operated at 220 V. A fuse wire of what rating must be used for it?

• 1 A

• 2 A

• 4 A

• 5 A

Multiple Choice

Two identical heater wires are first connected in series and then in parallel with a source of electricity. The ratio of heat produced in the two cases is :

• 2:1

• 1:2

• 4:1

• 1:4

Multiple Choice

You are given three bulbs 25 W, 40 W and 60 W. Which of them has the lowest resistance.

• 25 W Bulb

• 40 W bulb

• 60 W bulb

• Insufficient data

Multiple Choice

An electric heater can boil a certain amount of water in 10 minute and another heater can do it in 15 minute, both working at the same voltage. If the two heaters are connected in parallel across the same voltage as before how much time will they take to boil the same amount of water

• 9 min

• 12.5 min

• 7.5 min

• 6 min

Multiple Choice

When two electric bulbs of 40 W and 60 W are connected in parallel with a source, then the :

• bulb of 40 watt gives more light

• intensity of both bulbs are same

• intensity depends on the type of electric source (A.C. or D.C.)

• Bulb of 60 watt gives more light

Multiple Choice

A person connects four identical cells in series but one cell has its terminal reversed. The external resistance is 1 ohm. If each cell has an emf of 1.5 V and internal resistance of 0.25 ohm, the current flowing is :

• 4/3 A

• 3/4 A

• 1.5 A

• Zero

Multiple Choice

A person connects four identical cells in series but one cell has its terminal reversed. The external resistance is 1 ohm. If each cell has an emf of 1.5 V and internal resistance of 0.25 ohm, the current flowing is :

• 4/3 A

• 3/4 A

• 1.5 A

• Zero