1. Magnetic field lines represent the path of a magnetic field and have certain properties like not intersecting and forming closed loops. 2. The direction of a magnetic field induced by a current-carrying wire can be determined using the right-hand rule, and the strength of the field depends on the current and distance from the wire. 3. An electromagnet can be made by passing a current through a solenoid, inducing a magnetic field within it.

1. MAGNETIC EFFECTS OF ELECTRIC CURRENT
1. What are magnetic field lines? Give the properties of magnetic field lines.
Ans. Magnetic field lines are defined as: the path along which a free north pole tends to move.
Properties of magnetic field lines are:-
a) No two field lines can intersect each other.
b) The tangent to the curve of the field line gives the direction of magnetic field at that point .
c) Outside a magnet ,field lines diverge out at the north pole and converge at the south pole.
d) Field lines are closed loops.
2. (a)State the rule to find direction of magnetic field associated with current carrying straight conductor?
Ans. Right hand thumb rule: If the current carrying conductor is held in the right hand such that the thumb points
in the direction of current, then the direction of the curl of fingers will give the direction of magnetic field.
(b)On what factors magnetic field induced depends?
Ans. Proportional to amount of current flows,
Inversely proportional to distance from the wire.
3. How can you make an electromagnet?
Ans. By passing current through a solenoid, it behaves as an electromagnet.
**Draw magnetic field lines for current carrying solenoid.
4. **Draw a neat diagram to show magnetic field associated with a circular coil carrying current.
5. (a)State Fleming’s left and right hand rules.
Ans. Fleming’s Left Hand Rule –
Stretch your forefinger, middle finger , and thumb of left hand in three mutually perpendicular directions. If
the forefinger points in the direction of magnetic field, middle finger in the direction of current then thumb
represents the direction force acting on it.

2. Fleming’s Right hand rule
Stretch your thumb, forefinger, and middle finger of the right hand
Such that they are perpendicular to each other. If the forefinger points in the direction of magnetic field and
thumb points the direction of motion of the conductor then the middle finger points the direction of induced
current.
(b)Name the devices which work on the above rules.
Electric motor -. Fleming’s Left Hand Rule
Electric generator- Fleming’s Right hand rule
6. (a)What is electromagnetic induction?
The process of inducing electric current by changing magnetic fields is called electromagnetic induction.
7. (a)What is short circuiting and overloading?
Ans. When current in a circuit takes unintended path we call it a short circuit i.e. due to defective or damaged
wiring the live and neutral wires come in direct contact, resistance of the circuit becomes zero and extremely large
current flows through the ciruit. This is called short circuiting.
Overload: Overload is the condition when high current, more than the expected/rated value, flow through a circuit.
During overload the circuit may burn due to Joule 's heating and damage any appliance.
(b)How can you overcome its effect?
Short circuiting and overloading can be prevented by using an electric fuse in live wire.
8. (a)What is the principle behind the working of a fuse?
Ans. The electrical fuse works on the principle of Joule’s heating effect(heat given off by electrical energy).
The fuse is basically a wire which is attached to two terminals of a casing. All the electric current passes through it.
(b)What are the properties of a fuse wire?
Ans. It is made of tin or an alloy of copper and tin.
It should have low melting point and should be thin.
9. Write down the differences between electric motor and electric generator.
Ans.
Motor Generator
1)based on Fleming’s left hand rule 1)based on Fleming’s right hand rule
2)converts electrical energy to mechanical energy 2) converts mechanical energy to electrical energy.
3) It is based on magnetic effect of electric current. 3) It is based on electromagnetic induction.
10. (a)Show graphically alternating current and direct current.
Ans:
(b)What are the advantages of AC over Dc?
Ans. Ac can travel for longer distances when compared with dc.

3. (c)Find the time period of our line supply of frequency 50Hz?
Ans: T=1/f, T=1/50=0.020s.
10. On what factors force experienced by a current carrying conductor placed in magnetic field depends? Draw a circuit
to show the force exerted.
Ans. The direction of force experienced by a current carrying conductor placed in a magnetic field depends on (i)
the strength of electric current, (ii) strength of magnetic field (iii) length of the conductor and the direction of
the current in the conductor and the direction of the applied magnetic field. This is given by Fleming's left hand
rule.