WorksheetsElectricity
Total questions: 60
Worksheet time: 3hrs 0mins
Ohm's law states a relation between
Potential difference and resistance
Electric potential and current
Current and resistance
Potential difference and current
The p.d. across a 3 ohm resistor is 6 V. The current flowing in the resistor wil be:
1/2 A
1 A
2 A
6 A
An electrical appliance has a resistance of 25 ohm. When this electrical appliance is connected to a 230 V supply line, the current passing through it will be:
0.92 A
2.9 A
9.2 A
92 A
A current of 5 amperes flows through a wire whose ends are at a potential difference of 3 volts. Calculate the resistance of the wire.
0.6 ohm
1.6 ohm
6 ohm
0.06 ohm
Keeping the p.d. constant, the resistance of a circuit is halved. The current will become:
One forth
Four times
Half
Double
A p.d. of 10V is needed to make a current of 0.02A flow through a wire. What p.d. is needed to make a current of 250 mA flow through the same wire?
320V
125V
172V
250V
The area of cross section of a wire is doubled, then its resistance will be:
One forth
Four times
Half
Double
R is directly proportional to length of the conductor.
True
False
A wire is 1.0 m long, 0.2 mm in diameter and has a resistance of 10 ohm. Calculate the resistivity of its material?
3.56 × 10^-8 ohm m
0.36 × 10^-8 ohm m
3.14 × 10^-8 ohm m
3 × 10^-8 ohm m
What will be the resistance of a metal wire of length 2 m and area of cross section 1.55 × 10^-6 m², if the resistivity of the metal be 2.8 × 10^-8 ohm m?
0.06 ohm
0.036 ohm
0.36 ohm
3.6 ohm
See the details in the given circuit, the current of 0.24A also flows through the 12 ohm resistor which is connected in series. Calculate the potential difference across 12 ohm resistor.
4.5V
2.23V
2.88V
3.66V
Find V1, V2 and V3 which are the p.ds across the 1ohm, 2ohm and 3 ohm resistors in the following diagram, and the current is 5A.
1.0, 2.0 & 3.0
5.0, 10.0 & 15.0
5.0, 2.5 & 1.6
4.0, 3.0 & 2.0
Details are given in the above circuit. Calculate the total resistance in the circuit.
16 ohm
18 ohm
30 ohm
20 ohm
The lamps in a household circuit are connected in parallel because:
This way they require less current
If one lamp fails then the other remain lit
This way they require less Power
If one lit fails then the other also fail
Using the circuit given, state which of the following statement is correct?
When S1 and S2 are closed, lamps A and B are lit
With S1 open and S2 closed, A is lit and B is not lit
With S1 closed and S2 open A and B are lit
With S1 closed and S2 open, lamp A remains lit even if lamp B gets fused
Which of the following does not represent electrical power in a circuit?
I²R
IR²
VI
V²/R
How many joules are there in 1 kilowatt-hour
3.6 × 10⁴ J
3.4 × 10⁵ J
3.4 × 10⁸ J
3.6 × 10⁶ J
Which of the following is likely to be the correct wattage for an electric iron used in our homes?
60 W
250 W
850 W
2000 W
The SI unit of energy is
Joule
Coulomb
Watt
Ohm meter
An electric kettle for use on a 230 V supply is rated at 3000 W. For safe working, the cable connected to it should be able to carry atleast:
2A
5A
10A
15A
At a given time, a house iis supplied with 100 A at 220 V. How many 75 W, 220 V light bulbs could be switched on in the house at the same time (if they are connected in parallel)?
93
193
293
393
An electric heater is rated at 2 kW. Electrical energy costs Rs.4 per kW. What is the cost of using the heater 3 hours?
Rs.12
Rs.24
Rs.36
Rs.48
The heat produced by passing an electric current through a fixed resistor is proportional to the square of:
Magnitude of resistance of the resistor
Temperature of the resistor
Magnitude of current
Time for which current is passed
The heat produced in a wire of resistance 'x' and a current 'y' flows through it in time 'z' is given by:
x² × y × z
x × z × y²
y × z² × x
y × z × x
An electric fuse works on the:
Chemical effect of current
Magnetic effect of current
Lighting effect of current
Heating effect of current
The elements of electrical heating devices are usually made of:
Tungsten
Bronze
Nichrome
Argon
In a filament type light bulb, most of the electric power consumed appears as:
Visible light
Infra red rays
Ultraviolet rays
Fluorescent light
Which of the following is the most likely temperature of the filament of an electric light bulb when it is working on the normal 220 V supply line?
500°C
1500°C
2500°C
4500°C
A p.d. of 250 volts is applied across a resistance of 500 ohm in an electric iron. Calculate the heat energy produced in joules in 10 seconds.
1250 J
2500J
950 J
1500 J
Calculate the heat produced when 96000 coulombs of charge is transferred in 1 hour through a potential difference of 50 volts
4780.4 kj
3478.6 kj
4572.4 kj
4788.4 kj
A battery of 10 volt carries 20,000 C of charge through a resistance of 20 Ω. The work done in 10 seconds is
2 × 10³ joule
2 × 10⁵ joule
2 × 10⁴ joule
2 × 10² joule
See the diagram and find the resistance
5/3 ohm
3/5 ohm
4/3 ohm
2/5 ohm
Two resistors are connected in series gives an equivalent resistance of 10 Ω. When connected in parallel, gives 2.4 Ω. Then the individual resistance are
each of 5 Ω
6 Ω and 4 Ω
7 Ω and 4 Ω
8 Ω and 2 Ω
Two wires of same length and area made of two materials of resistivity ρ1 and ρ2 are connected in series to a source of potential V. The equivalent resistivity for the same area is
Two devices are connected between two points say A and B in parallel. The physical quantity that will remain the same between the two points is
Current
Voltage
Resistance
None of these
Calculate the current flows through the 10 Ω resistor in the following circuit.
1.2A
0.6A
0.2A
2.0A
A fuse wire repeatedly gets burnt when used with a good heater. It is advised to use a fuse wire of
More length
Less radius
Less length
More radius
A cooler of 1500 W, 200 volt and a fan of 500 W, 200 volt are to be used from a household supply. The rating of fuse to be used is
2.5 A
5.0 A
7.5 A
10 A
A cell, a resistor, a key, and an ammeter are arranged as shown in the circuit diagrams. The current recorded in the ammeter will be
Maximum in (i)
Maximum in (ii)
Maximum in (iii)
Same in all the cases
The slope of voltage (V) versus current (I) is called
Resistance
Conductance
Resistivity
Conductivity
Identify the correct circuit diagram:
(i)
(ii)
(iii)
(iv)
In the experimental verification of Ohm’s law, the function of Rheostat is
To change the voltage across the resistance
To change the current in the circuit
To balance the circuit
To control the circuit
What is the amount of current flowing through an electric press, if the amount of charge passing through a conductor in 10 minutes is 300 C?
30 A
0.3 A
0.5 A
5 A
Two electric bulbs have resistances in the ratio 1:2. If they are joined in series, the energy consumed in them is in the ratio.
2:1
1:2
4:1
1:1
Which of the following shows heating effect of electric current
Fuse wire
Electric iron
Electric heater
All of these
The resistivity does not change if
(a) the material is changed
(b) the temperature is changed
(c) the shape of the resistor is changed
(d) both material and temperature are changed
The electrical resistance of insulators is
High
Low
Zero
Infinitely high
A student carries out an experiment and plots the V-I graph 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
Find the current drawn from the battery by the network of four resistors Shown in the figure.
0.4 A
5.0 A
3.5 A
3.4 A
The temperature of a conductor is increased. The graph best showing the variation of its resistance is
Calculate the resistance of an aluminium cable of length 10 km and diameter 2.0 mm if the resistivity of aluminium is 2.7 × 10^-8 ohm m.
84 ohm
85 ohm
86 ohm
88 ohm
A battery and three lamps are connected as shown:
Which of the following statements about the currents at X, Y and Z is correct?
The current at Z is greater than that at Y
The current at Y is greater than that at Z
The current at X equals the current at Y
The current at X equals the current at Z
Assertion (A) : Tungsten metal is used for making filaments of incandescent lamps.
Reason (R) : The melting point of tungsten is very low.
Both A and R are true and R is the correct explanation of A
Both A and R are true but R is not the correct explanation of A
A is true but R is false
A is false but R is true
Assertion (A) : Longer wires have greater resistance and the smaller wires have lesser resistance.
Reason (R) : Resistance is inversely proportional to the length of the wire.
Both A and R are true and R is the correct explanation of A
Both A and R are true but R is not the correct explanation of A
A is true but R is false
A is false but R is true
Assertion (A) : Alloys are commonly used in electrical heating devices, like electrical iron,
toasters etc.
Reason (R) : Alloys do not oxidise (burn) readily at high temperatures
Both A and R are true and R is the correct explanation of A
Both A and R are true but R is not the correct explanation of A
A is true but R is false
A is false but R is true
Assertion (A) : When the resistances are connected between the same two points, they are said
to be connected in parallel.
Reason (R) : In case the total resistance is to be decreased, then the individual resistances are
connected in parallel.
Both A and R are true and R is the correct explanation of A
Both A and R are true but R is not the correct explanation of A
A is true but R is false
A is false but R is true
Assertion (A) : The resistivity of a substance does not depend on the nature of the substance
and temperature.
Reason (R) : The resistivity of a substance is a characteristic property of the material.
Both A and R are true and R is the correct explanation of A
Both A and R are true but R is not the correct explanation of A
A is true but R is false
A is false but R is true
Assertion (A) : The fuse is placed in series with the device.
Reason (R) : Fuse consists of a piece of wire made of a metal or an alloy of appropriate melting
point.
Both A and R are true and R is the correct explanation of A
Both A and R are true but R is not the correct explanation of A
A is true but R is false
A is false but R is true
Assertion (A) : Electron has a negative charge.
Reason (R) : Electrons move always from a region of higher potential to a region of lower potential.
Both A and R are true and R is the correct explanation of A
Both A and R are true but R is not the correct explanation of A
A is true but R is false
A is false but R is true
Assertion (A) : A voltmeter and ammeter can be used together to measure resistance but not power.
Reason (R) : Power is proportional to voltage and current.
Both A and R are true and R is the correct explanation of A
Both A and R are true but R is not the correct explanation of A
A is true but R is false
A is false but R is true
