# TEST – X ( Science )

advertisement ```TEST – X ( Science )
Time: 1 hour
ELECTRICITY and MAGNETISM
M.M.: 20
Q.1
What is a rheostat?
1
Q.2
State the rule to determine the direction of a force experienced by a current carrying straight conductor placed
in a magnetic field which is perpendicular to it.
1
Q.3
What happens to the resistance and resistivity of a metallic wire when its diameter is doubled?
2
Q.4
Why does the cord of an electric heater not glow while the heating element does?
2
Q.5
Two conducting wires of same material have equal length. One wire is thick and the other is thin. They are
connected to the same potential difference. In which wire the current will flow more easily? Give reason.
Q.6
2
Draw a diagram to show the magnetic field lines around a bar magnet. List any two properties of magnetic field
lines.
2
Q.7
What is an electromagnet? Why is steel not used to make an electromagnet?
2
Q.8
What do you mean by an alternating current and direct current? How many times an AC current will change its
direction if its frequency is 50 Hz?
Q.9
(a) Distinguish between the terms ‘overloading’ and ‘short – circuiting’ as used in domestic circuits.
(b) Why are the coils of electric toasters made of an alloy rather than a pure metal?
Q.10
2
3
Two lamps, one rated 40 W at 220 V and the other 60 W at 220 V, are connected in parallel to the electric
supply at 220 V.
(a) Draw a circuit diagram to show the connections.
(b) Calculate the current drawn from the electric supply.
(c) Calculate the total energy consumed by the two lamps together when they operate for one hour.
3
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