Answer:
![emf=26\ V](https://img.qammunity.org/2021/formulas/physics/college/ykvk4aqd9jy4uoz22vu6y549b0i7r254lh.png)
Step-by-step explanation:
Given:
no. of turns in the first coil,
![n_1=7](https://img.qammunity.org/2021/formulas/mathematics/college/f2441c7aqxv9fcoo7r1nm1insfqbnrsybv.png)
no. of turns in the second coil,
![n_2=13](https://img.qammunity.org/2021/formulas/physics/college/a4u5jsfge4qs31zeikatjhzy880sjmqdjh.png)
the change in flux through the secondary coil,
![d\phi=2.7-2.1=0.6\ Wb](https://img.qammunity.org/2021/formulas/physics/college/dkd5dnh39s9os3vvoa7d7zaa1d7b53tkit.png)
time taken for the change in flux,
![dt=0.3\ s](https://img.qammunity.org/2021/formulas/physics/college/hj4j3qkmobv50rfy5k7zayn0aux0tsnt7h.png)
- According to the Faraday's law there will be an emf induced in the coil associated with the rate of change in magnetic flux.
This emf is mathematically given as:
![emf=n_2* (d\phi)/(dt)](https://img.qammunity.org/2021/formulas/physics/college/dilzgrt393mvgyv9yxm31r8t8sammjk91q.png)
(we take no. of turns of the second coil because the rate of change in flux is associated with the second coil)
![emf=26\ V](https://img.qammunity.org/2021/formulas/physics/college/ykvk4aqd9jy4uoz22vu6y549b0i7r254lh.png)