Vardaan Learning Institute

Ans: (a) Parallel straight lines
This indicates that the magnetic field is uniform inside the solenoid.

Ans: (b) Fleming's Left Hand Rule
Used to find direction of force (motion) on a current carrying conductor in a magnetic field.

Ans: (c) Earth wire
Live is Red/Brown, Neutral is Black/Blue, Earth is Green.

Ans: (b) 50 Hz
AC supply in India reverses direction 100 times in a second (50 Hz).

Ans: (c) It increases
Magnitude of magnetic field is directly proportional to the current ($B \propto I$).

Ans: (b) Electromagnet
Commercial motors use electromagnets instead of permanent magnets to produce a stronger field.

Ans: (c) Same at all points
Inside a solenoid, field lines are parallel, indicating uniform field.

Ans: (c) Magnetic Needle
A compass needle deflects in the presence of a magnetic field.

Ans: (b) If they cross, there would be two directions of field at one point, which is impossible
Magnetic field at a point has a unique direction.

Ans: (c) Producing induced current in a coil due to relative motion between a magnet and the coil
This is the definition of EMI.

Ans: (a) Both A and R are true and R is the correct explanation of A.
Current creates a magnetic field which exerts a force on the magnetic compass needle, deflecting it.

Ans: (b) Both A and R are true but R is not the correct explanation of A.
A is true. R is true (they are imaginary representations). But R explains nothing about intersection. Reason for A is uniqueness of field direction.

Ans: (a) Both A and R are true and R is the correct explanation of A.
Soft iron is ferromagnetic and magnetizes easily, drastically increasing field strength.

Ans: (a) Both A and R are true and R is the correct explanation of A.
Earthing ensures that if there is leakage, current goes to earth, preventing severe shock to user.

(Diagram required)
Characteristics:
1. Lines emerge from North Pole and merge at South Pole (outside magnet).
2. No two field lines intersect each other.

Safety device used to protect circuits from damage due to excessive current. It works on the heating effect of electric current. If current exceeds rating, the fuse wire melts and breaks the circuit.

Imagine holding a current-carrying straight conductor in your right hand such that the thumb points towards the direction of current. Then your fingers wrap around the conductor in the direction of the field lines of the magnetic field.
It determines the direction of magnetic field lines.

1. Electromagnet is temporary (only works when current flows), Permanent magnet's magnetism is permanent.
2. Electromagnet strength can be varied (by changing current/turns), Permanent magnet strength is fixed.
3. Electromagnet polarity can be reversed, Permanent magnet polarity is fixed.

1. If one appliance fails, entire circuit breaks.
2. Each appliance cannot be operated independently with its own switch.
(Also: Voltage drops across components).

Function: To provide a low resistance path for leakage current.
Necessary to protect user from electric shock if live wire touches the metallic body of the appliance.

(i) A coil of many circular turns of insulated copper wire wrapped closely in the shape of a cylinder. (Diagram: Identical to bar magnet field).
(ii) Increase current; Increase number of turns.
(iii) It becomes an electromagnet (field strength increases significantly).

(i) Short Circuit: When Live and Neutral wires come in direct contact. Resistance becomes zero, current becomes huge.
Overloading: Drawing more current than the circuit rating (e.g., connecting too many appliances to one socket).
(ii) Proton (positive charge) moving East = Direction of Current is East. Magnetic Field is North.
Apply Fleming's Left Hand Rule: Force acts UPWARD (out of the page).
(iii) Fleming's Left Hand Rule.

(i) Magnetic Compass.
(ii) The direction of deflection will also be reversed.
(iii) Fleming's Left Hand Rule: Stretch thumb, forefinger, and middle finger of left hand mutually perpendicular. If forefinger points to magnetic field, middle finger to current, then thumb points to force.

(i) Red.
(ii) 50 Hz.
(iii) Potential Difference: 220 V. Earth Wire: Provides a safety path for leakage current to prevent shocks from metallic appliances.