# Homework Help: Induction & Tranformer Problems

1. Feb 15, 2004

### mustang

Problem 1.
A single circular loop with a radius of 28cm is palced in a uniform external magnetic field with a strength of 0.54 T so that the plane of the coil is perpendicular to the field. The coil is pulled steadily out of the field in 0.35s.
Find the average induced emf during this interval. Asnwer in V.
Note: what formula should i use?

Problem 5.
A 38-turn coil with an area of 1.8*10^-3 m^2 is dropped from a position where B=0.0T to a new position where B= 0.68T. The displacement occurs in 0.29 s and the area of the coil is perpendicular to the magnetic field lines.
What is the resulting average emf induced in the coil? Answe in V.
Note: How do I start?

Problem 7.
A step-up transformer for long-range transmission of electric power is used to create a potential difference of 129530 V across the secondary. The potential difference across the primary is 161 V and the secondary has 26000 turns.
How many turns are in the primary? Answer in units of turns.
Note: What is the formula I should?

Problem 10.
A transformer is used to convert 120 V to 16V in order to power a toy electric train. There are 240 turns in the primary.
How many turns should there be in the secondary? Answer in units of turns.
Note: I don't know where to start.