CBSE X Magnetic Effects of Electric Current practice questions

Question 1

Choose the incorrect statement about magnetic field lines.

Accepted Answer

Parallel equally spaced field lines represent zero field strength

Answer

The compass north pole indicates field direction

Answer

Magnetic field lines form closed curves

Answer

Closer field lines represent a stronger field

Question 2

For a nonzero charged particle in a nonzero magnetic field,which condition makes the magnetic force zero?

Accepted Answer

The particle is stationary

Answer

It moves perpendicular to the field

Answer

It moves at 45° to the field

Answer

It moves at 60° to the field

Question 3

A charged particle moves parallel to a magnetic field. What is the magnetic force?

Accepted Answer

Zero

Answer

qvB

Answer

2qvB

Answer

Always vertically upward

Question 4

How does a current-carrying solenoid behave, and what is a common use?

Accepted Answer

Like a bar magnet; it can form an electromagnet with a soft-iron core

Answer

Like an electric insulator; used only to block current

Answer

Like an uncharged plastic rod; used to neutralise acid

Answer

Like a resistor with no magnetic field; used to split water

Question 5

For a circular current loop, which rule gives the field direction from the current direction?

Accepted Answer

Right-hand thumb rule: curl fingers with current; thumb gives the central field direction

Answer

Field always points upward regardless of current

Answer

Left-hand rule for a moving motor conductor only

Answer

Field points opposite at every point simultaneously

Question 6

What is a solenoid?

Accepted Answer

A long coil made of many closely wound turns of insulated wire

Answer

A single straight uninsulated wire

Answer

A permanent magnet without a coil

Answer

An insulating rod only

Question 7

At a fixed distance from a long straight wire, how does magnetic-field strength depend on current magnitude?

Accepted Answer

It is directly proportional to current

Answer

It is inversely proportional to current

Answer

It is independent of current

Answer

It is proportional to the square of the distance only

Question 8

Why can stepping up an AC transmission voltage reduce resistive line losses for the same transmitted power?

Accepted Answer

Higher voltage allows lower current, reducing I²R loss

Answer

Higher voltage requires proportionally higher current

Answer

Line resistance becomes exactly zero

Answer

A transformer destroys the power loss after it occurs