REVISION SHEET 01
1.
Calculate the number of electrons constituting 0.1 coulomb of charge.
2.
0.8 coulomb charge flows through a given area of cross–section of a conductor in 8 seconds. Calculate the
current flowing through the conductor.
3.
Calculate the amount of charge that would flow in 2 hours through an element of an electric bulb drawing
current of 0.25 A.
4.
6.25 x 10 electrons flow from one end to another end of the conductor in 5 seconds. Find the current flowing
through the conductor.
5.
A current of 0.5 A passes through a conductor in 2 seconds. How many electrons flow through this conductor
-19
form one end to the other end during this interval of time? Charge on each electron is 1.6 x 10 C.
6.
An electric bulb draws a current of 0.2A, when the voltage is 220 volts. Calculate the amount of electric
charge flowing through it in one hour.
7.
In a particular television tube, a beam of electrons is emitted. The beam current is 80m A. How many
electrons strike the screen of TV every second ? Also find the total charge striking the screen in 2 minutes.
8.
If a current of 0.1 A flows through a conductor, (i) find the number of electrons crossing the area of crosssection per second and (ii) find the net flow of charge if this current is maintained for one hour.
a
18
Answers:
17
1. 6.25 x 10
4. 0.2A
17
7. 5 x 10 , 9.6C
2. 0.1A
18
5. 6.25 x 10
17
8. 6.25 x 10 , 360C
3. 1800C
6. 720C
REVISION SHEET 02
1.
Current in a wire is due to the flow of electrons in the wire. Although the drift speeds of electrons in the wire is
very small, yet an electric bulb lights up as soon as the switch is on. Explain, Why ?
2.
24 J work is done in moving a charge of 6 C between two points. Calculate the potential difference between
these two points.
3.
Calculate the potential at a point if 5 joule work is done in moving 1 coulomb charge.
4.
24 J work is done in moving a charge q between two points having potential difference of 12 volt. Find the
value of charge q.
5.
Graphs between electric current and potential difference across two conductors A and B are plotted as shown
in figure. Which of the two conductors has more resistance? Give reason.
6.
The resistivity of a few materials are given below :
S. No.
1
2
3
Material
Silver
Copper
Aluminium
Resistivity
-8
-8
-8
1.6 × 10
1.62 × 10
2.6 × 10
(Ωm)
4
5
Tungsten
5.2 × 10
-8
Nickel
6.84 × 10
-8
Which material is the best conductor ?
7.
8.
The electrical resistivity of few materials is given below in ohm-meter. Which of these materials can be used
for making element of a heating device?
Material
Resistivity (ohm metre)
A
6.84 × 10
-8
B
1.60 × 10
-8
C
2.30 × 10
D
1.00 × 10
E
2.50 × 10
F
4.40 × 10
17
-6
12
-8
Two wires A and B are of equal lengths, different cross-sectional areas and made of same metal.
(a) (i) Name the property which is same for both the wires,(ii) Name the property which is different for both the
wires.
(b) If the resistance of wire A is four times the resistance of wire B, calculate (i) the ratio of the cross-sectional
areas of the wire and (ii) the ratio of the radii of the wires.
Answers:
2. 4V
5. A
3. 5V
8.(b) 1:4, 1:2
4. 2C