Magnetism And Electromagnetism

Question 1

Factors that effect the strength of a magnetic field

Answer 1

Current in the coil, number of turns in the wire, material of the core

Question 2

Direction of force

Answer 2

Perpendicular to the direction of the current and magnetic field

Question 3

Flemings Left Hand Rule

Answer 3

Hold the thumb and first two fingers of the left hand at right angles to each other with the First finger pointing in the direction of the Field and the seCond finger in the direction of the Current then the Thumb points in the direction of the Thrust

Question 4

Direct vs alternating current

Answer 4

In a direct current the electrons flow in one direction only

In an alternating current the direction of the electron flow reverses regularly

Question 5

Electromagnetic induction

Answer 5

When the magnet is stationary there is no induced current

An alternating current can be induced by rotating the bar magnet close to the coil

This is the basis for generating electricity

Question 6

A.C generators

Answer 6

Used in the generation of electricity, in their simplest form consist of a coil of war rotated between the poles of a magnet

Question 7

Step up vs step down transformer

Answer 7

A step up transformer has more turns on the secondary than on the primary and Vs is greater than Vp

A step down transformer has more turns on primary than on the secondary and Vp is greater than Vs

Question 8

Transformer efficiency formula

Answer 8

Ns Vs
— = —
Np Vp

Question 9

Role of step up and step down transformers

Answer 9

A step up transformer allows for electricity to be sent across long distances in wires

A step down transformer allows that electricity to reduced to a safe level for house appliances