Question

The emf induced across the ends of a conductor due to its motion in a magnetic field is called motional emf. It is produced due to magnetic Lorentz force acting on the free electrons of the conductor. For a circuit shown in the figure, if a conductor of length l moves with velocity v in a magnetic field B perpendicular to both its length and the direction of the magnetic field, then all the induced parameters are possible in the circuit.

A bicycle generator creates 1.5 V at 15 km/hr. The EMF generated at 10 km/hr is ______.

Options

• 1.5 volts

• 2 volts

• 0.5 volts

• 1 volts

Answer 1

A bicycle generator creates 1.5 V at 15 km/hr. The EMF generated at 10 km/hr is 1 volts.

Explanation:

Emf induced, ε = Blv

Here, `vec"B", vecl and vec "v"` are mutually perpendicular

For given B and l. ε ∝ v.

`therefore epsilon_1/epsilon_2 = "v"_1/"v"_2`

Here, ε₁ = 1.5 V, v₁ = 15 km/hr = `15 xx 5/18` ms^-1

v₂ = 10 km/hr = `10 xx 5/18`ms^-1, ε₂ = ?

So, `1.5/epsilon_2 = (15 xx 5/18)/(10 xx 5/18) = 3/2`;

`epsilon_2 = 1 "V"`