# Thread: how many loops in a coil

1. ## how many loops in a coil

In each of two coils the rate of change of the magnetic flux in a single loop is the same. The emf induced in coil 1, which has 161 loops, is 2.78 V. The emf induced in coil 2 is 4.96 V. How many loops does coil 2 have?

can someone work this one out please.

2. We use that: $U_i=N\cdot\frac{\Delta\Phi}{\Delta t}$.
So $\frac{\Delta\Phi}{\Delta t}=\frac{2.78}{161}$. Therefore $N_2=\frac{U_2}{\frac{\Delta\Phi}{\Delta t}}=\frac{4.96}{\frac{2.78}{161}}\approx \mathbf{287}$.

3. Thankyou, now i can see how it should be set up.