Electricity

A piece of wire of resistance R is cut into five equal parts. These parts are then connected in parallel. If the equivalent resistance of this combination is R', then the ratio $\frac{R}{R'}$ is:
1. $\frac{1}{25}$
2. $\frac{1}{5}$
3. 5
4. 25
Which of the following terms does not represent electrical power in a circuit:
1. $I^{2} R$
2. $I R^{2}$
3. $V I$
4. $\frac{V^{2}}{R}$
An electric bulb is rated at 220 V and 100 W. When it is operated on 110 V, the power consumed will be:
1. 100 W
2. 75 W
3. 50 W
4. 25 W
Two conducting wires of the same material and of equal length and equal diameter are first connected in series and then in parallel in an electric circuit. The raio of the heat produced in series and parallel combinations would be:
1. 1 : 2
2. 2 : 1
3. 1 : 4
4. 4 : 1
Electric charge is expressed in:
1. Volt
2. Joule
3. Coulomb
4. Ohm
In the given figure, the resistors:
1. $6 Ω$ , $3 Ω$ and $9 Ω$ are in series
2. $9 Ω$ and $6 Ω$ are in parallel and the combination is in series with $3 Ω$
3. $6 Ω$ , $3 Ω$ and $9 Ω$ are in parallel
4. $3 Ω$ and $6 Ω$ are in parallel and the combination is in series with $9 Ω$
When the distance between two charged particles is halved, the force between them becomes:
1. One - half
2. Double
3. One - fourth
4. Four times
The minimum value of charge cannot be less than:
1. $1.6 \times 10^{- 19} C$
2. $3.2 \times 10^{- 19} C$
3. 1 C
4. $3 \times 10^{9} C$
The potential difference across the 3 Ω resistor in the following diagram is:
1. $\frac{1}{9} V$
2. $\frac{1}{2} V$
3. 2 V
4. 1 V
You are given four ammeters A, B, C and D having least counts mentioned below:
(I) Ammeter A with least count 0.25 A
(II) Ammeter B with least count 0.5 A
(III) Ammeter C with least count 0.05 A
(IV) Ammeter D with least count 0.1 A
Which of the ammeters would you prefer for doing an experiment to determine the equivalent resistance of two resistances most accurately, when connected in parallel?
1. Ammeter A
2. Ammeter B
3. Ammeter C
4. Ammeter D
The resistance of a straight conductor is independent of:
1. Temperature
2. Material
3. Cross - sectional area
4. Shape of cross - section
The resistivity of a wire:
1. Varies with its length
2. Varies with its cross - section
3. Varies with its mass
4. Is independent of length, cross-section and mass of the wire
Two resistances $R_{1}$ and $R_{2}$ are connected in parallel. Their equivalent resistance is:
1. $R_{1} + R_{2}$
2. $\frac{R_{1} R_{2}}{R_{1} + R_{2}}$
3. $\frac{R_{1} + R_{2}}{R_{1} R_{2}}$
4. $\sqrt{R_{1} R_{2}}$
If a wire of resistance R is melted and recast to half its length, the new resistance of the wire will be:
1. $\frac{R}{4}$
2. $\frac{R}{2}$
3. R
4. 2R
Three resistances of $2 Ω$ , $4 Ω$ and $8 Ω$ are connected in parallel. Their equivalent resistance is:
1. $14 Ω$
2. $10 Ω$
3. $\frac{8}{7} Ω$
4. Between $2 Ω$ and $8 Ω$
If n equal resistances are first connected in series and then connected in parallel, the ratio of the maximum to the minimum resistance is:
1. n
2. $\frac{1}{n^{2}}$
3. $n^{2}$
4. $\frac{1}{n}$
If $R_{1}$ and $R_{2}$ are the resistances of filaments of a 400 W and a 200 W lamp, designed to operate on the same voltage, then:
1. $R_{1} = 2 R_{2}$
2. $2 R_{1} = R_{2}$
3. $4 R_{1} = R_{2}$
4. $R_{1} = R_{2}$
A current of 2 A passes through a conductor and produces 80 J of heat in 10 seconds. The resistance of the conductor is:
1. $0.5 Ω$
2. $2 Ω$
3. $4 Ω$
4. $0.20 Ω$
A house has 10 tubes each of 40 W. If all the tubes are lighted for 10 hours and if the cost of one unit of electric energy is Rs 2.50, the total cost of electricity consumption is:
1. Rs 100
2. Rs 20
3. Rs 25
4. Rs 10
What is the rate of flow of electric charges called?
1. Electric potential
2. Electric conductance
3. Electric current
4. None of these
Which of the following is the SI Unit of Electric Current?
1. Ohm
2. Ampere
3. Volt
4. Faraday
Which instrument is used for measuring electric potential?
1. Ammeter
2. Galvanometer
3. Voltmeter
4. Potentiometer
When one unit electric charge moves from one point to another point in an electric circuit, then the amount of work done in joules is known as?
1. Electric current
2. Electric resistance
3. Electric conductance
4. Potential difference
The hindrance presented by material of conductor to the smooth passing of electric current is known as:
1. Resistance
2. Conductance
3. Inductance
4. None of these
The resistance of a conductor is directly proportional to:
1. Its area of cross-section
2. Density
3. Melting point
4. Length
The purpose of a rheostat is:
1. Increase the magnitude of current only
2. Decrease the magnitude of current only
3. Increase or decrease the magnitude of current
4. None of these
Point to be kept in mind for verification of Ohm’s Law is:
1. Ammeter and voltmeter should be connected in series
2. Ammeter should be connected in series and voltmeter in parallel
3. Ammeter should be connected in parallel and voltmeter in series
4. Ammeter and voltmeter should be connected in parallel
When a 40 V battery is connected across an unknown resistor there is a current of 100 mA in the circuit. Find the value of the resistance of the resister:
1. $5000 Ω$
2. $800 Ω$
3. $0.8 Ω$
4. None of these
A fuse wire is inserted in:
1. Live wire
2. Nuetral wire
3. Earth wire
4. May be connected in any line
An electrical appliance has a resistance of $25 Ω$ . When this electrical appliance is connected to a 230 V supply line, the current passing through it will be:
1. 0.92 A
2. 2.9 A
3. 9.2 A
4. 92 A

Electricity

Quiz