Download SA1 REVISION WORKSHEET 2_0

Buds Public School, Dubai
PHYSICS Revision Worksheet
Name:________________________
Class:10
Sec:___
1. Define the term ‘resistivity’ of a material.
Resistivity is the resistance offered by a conductor having unit length and unit
area of cross section
2. Define S.I. unit of magnetic field. Under what condition does a moving charge
experience:
(i) maximum force (ii) minimum force
S.I unit of magnetic field is Tesla(T).
1)Maximum force when the applied magnetic field is perpendicular to its
motion.2) Minimum when M.F is papallel.
3. Two electric lamps of 100 W and 25 W respectively are connected in parallel
to a supply voltage of 200 V. Calculate the total current flowing through the
circuit.
P=VI, I=P/V
I1=100/200=0.5A
I2=25/200=0.13A
I=I1+I2=0.5+0.13=0.63A
4. (a) What is overloading? Why does a fuse wire melt on overloading?
(b) Why does short-circuit lead to the fuse wire burning?
Refer notes on domestic circuits.
5. Compare and contrast Biomass and Hydroelectricity as source of energy.
Refer notes.
6. (a) A current carrying aluminium rod AB is placed in a magnetic field. The
direction of magnetic field is vertically upward. How do we think the
displacement of rod AB will be affected if:
the current in the rod AB is increased.
a stronger horseshoe magnet is used.
length of the rod AB is increased?
Ans: The force experienced by a current carrying conductor in a magnetic field is
F=IlB. The force is directly proportional to current, magnetic field strength and
length of the conductor. Therefore in the above three cases displacement of the
road will be more.
7. How does a solenoid behave like a magnet? Can you determine the north and
south poles of a current carrying solenoid with the help of bar magnet?
A solenoid is a long coil of circular loops of insulated copper wire. Magnetic
field lines are produced around the solenoid when a current is allowed to flow
through it. The magnetic field produced by it is similar to the magnetic field of
a bar magnet. The field lines produced in a current-carrying solenoid is shown
in the following figure. when the north pole of a bar magnet is brought near the
end connected to the negative terminal of the battery, the solenoid repels the
bar magnet. Since like poles repel each other, the end connected to the negative
terminal of the battery behaves as the north pole of the solenoid and the other
end behaves as a south pole. Hence, one end of the solenoid behaves as a north
pole and the other end behaves as a south pole.
8. List the properties of magnetic lines of force.
A current through a horizontal power line flows in east to west direction. What
is the direction of magnetic field at a point directly below it and at a point
directly above it?
Properties:
(i) They represent the magnetic field.
(ii) They are directed from north to South Pole outside a magnet and from
south to North Pole inside a magnet.
(iii) The field lines are closed curves.
(iv) The strength of magnetic field in a region is determined by closeness of
the field lines in that region.
(v) The closer the field lines are, greater will be the field strength and vice–
versa.
(vi) No two field lines ever cross each other as it would mean two different
directions of field at point of intersection, which is not possible.
viii) The parallel lines represent the uniform magnetic field whereas
converging lines or diverging lines represents the non uniform magnetic field.
The current is in the east-west direction. Applying the right-hand thumb rule, we
get that the direction of magnetic field at a point below the wire is from north to
south. The direction of magnetic field at a point directly above the wire is from
south to north
9. Draw the patterns of magnetic field lines through and around a current carrying
solenoid. What does the magnetic field pattern inside the solenoid indicate?
(A)How can this principle be utilized to make an electromagnet?
(B) State two ways by which strength of this electromagnet can be increased?
For fig. refer notes.
The field lines inside the solenoid are parallel straight lines. This indicates that
the magnetic field is uniform and is therefore, same at all points inside it.The
field lines outside the solenoid are curved lines. This indicates that the
magnetic field is non-uniform.
A) Electromagnet is a magnet formed by the magnetization of a piece of a
magnetic material (such as soft iron) by inserting it into a solenoid.
B) The magnetic field (strength) of an electromagnet depends upon:
(i) Amount of current passing through the coil
(ii) Number of turns of the coil
(iii) Nature of core material present inside coil. So by increasing current or
number of turns we can increase the strength of electromagnet.
10. (a) With the help of an activity, explain the method of inducing electric
current in a coil with a moving magnet. State the rule used to find the direction
of electric current thus generated in the coil.
(b) Two circular coils P and Q are kept close to each other, of which coil P
carries a current. What will you observe in Q:
(i) if current in the coil P is changed.
(ii) if both the coils are moved in the same direction with the same speed?
Give reason.
11.(a) Calculate the resistance of the wire using the graph.
Resistance=slope of this graph
=0.6/0.2=0.3 ohm
(b)
line?
R/n=V/I
n=R*I/V
=176*5/220
=4
(c) Define electric power. Derive relation between power, potential difference
and resistance.
Refer notes.
12.Find the equivalent resistance across the two ends A and B of the circuit given
below
R2||R3||R4
1/RP=1/15+1/15+1/15
=3/15=1/5
RP=5ohms
R6||R7
1/RP=1/40+1/60
=5/120=1/24
RP=24 ohms
The total resistance is 10+5+6+24=45 ohms.
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