At a certain instant, coil A is in a 10-T external magnetic field and coil B is in a 1-T external magnetic field. Both coils have the same area and are oriented at right angles to the field. Which coil will have a greater emf induced in it

Impossible to know without more information about the fields.

Explanation:

Changing the magnetic field induces the external magnetic field, but the information regarding magnetic field variation is not provided. We need to required more information for this

Therefore according to the above explanation the correct option is Impossible to know without more information about the fields.

Hence, the b option is correct

the current is 0.6

voltage ÷ resistance = current

so 12 ÷ 20 = 0.6