A step-up transformer must increase the voltage fivefold. What must be the ratio of secondary coil turns to primary coil turns?
A1:5
B5:1
C25:1
D10:1
Answer & Solution
Correct answer: B. 5:1
1. The transformer equation states that the ratio of secondary to primary voltage equals the ratio of secondary to primary turns (Vs/Vp = Ns/Np).
2. The transformer needs to increase voltage fivefold, so Vs/Vp = 5.
3. By the transformer equation, Ns/Np must also equal 5, i.e. a 5:1 ratio of secondary to primary turns.
4. 1:5 would step the voltage down, not up; 25:1 and 10:1 do not match a simple fivefold increase.
5. So the secondary coil needs 5 times as many turns as the primary coil.
_Source: OpenStax Physics Ch 20 "Magnetism", p.690 §20.2 Motors, Generators, and Transformers_
Related questions
All magnetic effects are explained using currents rather than poles because monopoles are:A charge moving parallel to a magnetic field experiences a magnetic force that is:A ferromagnetic material becomes strongly magnetic when its domains are:Cutting a bar magnet in half produces two magnets rather than two monopoles because:The similarity noted between magnetic poles and electric charges is that unlike ones:A solenoid is described as a long coil of wire with:The magnitude of the magnetic force on a moving charge depends on the angle between the fiThe magnetic force on a charge moving in a magnetic field is often called the: