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Electricity
Class 10
Practice Questions
1)
The
correct formula that shows the relationship between potential difference and
current is
a)
I
= R/V
b)
I
= VR
c)
V
= I/R
d)
R
= V/I
2)
Device
used to measure the rate of current in a circuit is
a)
Ammeter
b)
Voltmeter
c)
Galvanometer
d)
Battery
3)
Ohm
is SI unit of
a)
Potential
difference
b)
Resistance
c)
Electric
current
d)
Electric
charge
4)
An
electric bulb is connected to a 220V generator. The current is 0.5A. then the
power of the bulb is
a)
100W
b)
110W
c)
120W
d)
200W
5)
The
material used in the filament of bulb is
a)
Sodium
b)
Tungsten
c)
Aluminium
d)
Copper
6)
A
piece of wire of resistance R is cut into 5 equal parts. These parts are then
connected in parallel. If the equivalent resistance of the combination is R1,
then the ratio R : R1 is
a)
1
: 25
b)
1
: 5
c)
5
: 1
d)
25
: 1
7)
SI
unit of current is ___
a)
Ohm
b)
Watt
c)
Joule
d)
Ampere
8)
Instrument
used to measure potential difference is ____
a)
Rheostat
b)
Voltameter
c)
Battery
d)
Voltmeter
9)
Three
resistors of 4W, 5W and 20W are connected in parallel. Their
combined resistance is ___
a)
2W
b)
4W
c)
5W
d)
20W
10)
The
symbol ------^^^^^^------ represents
a)
Ammeter
b)
Voltmeter
c)
Resistor
d)
rheostat
11)
An
electric motor takes 5A from 220V electric source. The power of motor is
a)
1100W
b)
44W
c)
225W
d)
440W
1)
State
Ohm’s law. On which factors the resistance of the conductor depends? Mention the SI unit of electric power.
2)
State
Joules law of heating. Name any two devices that work on the application of
this law.
3)
Why
the alloys like nichrome is used in electrical heating devices?
4)
What
are the advantages of connecting electrical devices in parallel in an electric
circuit instead of connecting then in series?
5)
How
are ammeter and voltmeter connected in an electric circuit?
6)
What
is the function of earth wire?
7)
Why
is the series arrangement not used for domestic circuits?
8)
How
you would connect three resistors each of resistance 6W so that the combination has a
resistance of 9W and 2W?
9)
How
are ammeter and voltmeter connected in a electric circuit? What are their
functions?
10)
Define
potential difference
11)
How
does the resistance of wire vary with the area of cross section?
12)
What
is electric potential? What is its SI unit? Name the device used to measure the
potential difference
Problems
1)
100J
of heat is produced each second in a 4W
resistance. Find the potential difference across the resistor.
2)
The
resistors R1, R2 and R3 having values 10W, 20W
and 60W respectively are
connected in parallel to a battery of 24V in an electric circuit. Calculate the
following.
a)
The
current flowing through each resistor
b)
Total
current in the circuit
c)
Total
resistance of the circuit
3)
An
electric refrigerator rated 500W operates 8 hours a day. What is the cost of
the energy to operated it for 30days at Rs.5 per one KWh?
4)
An
electric bulb is connected to a 220V generator. The current is 2A. Find the
power and resistance of the bulb.
5)
The
potential difference between the terminals of an electric heater is 60V, when
it draws a current of 4A from the source. What current will the heater draw if
the potential difference is increased to 120V?
6)
An
electric iron of resistance 20W takes current of
5A Calculate the heat developed in 30s.
7)
Calculate
the power rating of a heater coil when used on 220V supply taking 5A.
8)
A
potential difference of 220V is applied across a resistance of 400W in an electrical appliance. Calculate
the current drawn and heat energy produced in 20 seconds.
9)
Three
resistors 5W, 10W and 15W are connected in parallel. A 12V
battery is connected in series in series in the circuit. Find the effective
resistance and current drawn.
10)
Calculate
the resistance of 1000cm long copper wire of area of cross section 2 x 10-2cm2.
The resistivity of copper is 1.623 x 10-8Wm.
11)
A
wire of a given material having length l and area of cross section A has a
resistance 4W. What would be
the resistance of the another wire of same material having length l/2 and area
of cross section 2A.
12)
Compare
the power used in the 2W resistor in the
following circuits
i)
A
6V battery in series with 1W and 2W resistors
ii)
A
4V battery in parallel with 12W and 2W resistors
Diagrams
1)
Draw
the symbols of the following : i) Rheostat
ii) wires crossing without joining
2)
Diagram
of a circuit consisting of battery, ammeter, voltmeter, and three resistors
connected in parallel.
3)
Diagram
of electric circuit comprising of electric cell, electric bulb, ammeter and
plug key
4)
Draw
a neat diagram showing the arrangement of resistors R1, R2 and R3 in series
mode.
5)
Draw
the symbols for the following
i)
An
electric cell ii) variable
resistor iii) open plug key
iv)
battery v) resistance vi) electric bulb
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