Question

The coercively of a bar magnet is \(100 \mathrm{~A} / \mathrm{m}\). It is to be diamagnetism by placing it inside a solenoid of length \(100 \mathrm{~cm}\) and number of turns 50 . The current flowing through the solenoid will be (a) \(4 \mathrm{~A}\) (b) \(2 \mathrm{~A}\) (c) \(1 \mathrm{~A}\) (d) Zero

Short answer

The current flowing through the solenoid for diamagnetism is \(2 \mathrm{~A}\), which corresponds to option (b).

Step-by-step solution

Write down the given values

The given values are: Coercivity of the bar magnet \(H_{c} = 100 \mathrm{~A}\) \(/\) \(\mathrm{m}\), Length of the solenoid \(l = 100 \mathrm{~cm}\) \(= 1 \mathrm{~meter}\) (converting to meters), Number of turns of the solenoid \(N = 50\).

Use the coercive field formula

The coercive field formula is \(H_{c} = NI / l\). We can solve this formula for the current \(I\): \(I = \frac{H_{c} \cdot l}{N}\)

Substitute the given values in the formula

Now insert the given values into the formula to find the current \(I\): \(I = \frac{(100 \mathrm{~A} / \mathrm{m}) \cdot (1 \mathrm{~m})}{50}\)

Calculate the current

Simplify the expression to get the current \(I\): \(I = \frac{100 \mathrm{~A}}{50} = 2 \mathrm{~A}\) The current flowing through the solenoid for diamagnetism is \(2 \mathrm{~A}\), which corresponds to option (b).