Booklets

Question 1

Define elastic limit

Answer 1

Force/stress/strain/extension beyond which the material does not return to its original length when the load is removed

Question 2

State Kirchhoff’s first law

Answer 2

SUM of currents into a JUNCTION = SUM of currents out of the JUNCTION

Question 3

Describe a plane polarised wave

Answer 3

Transverse wave/vibrations in plane normal to the direction of energy propagation
Oscillations in one direction only/ confined to a single plane

Question 4

Diffracted light from two slits produce an interference pattern consisting of bright and dark lines formed on the screen. Explain in terms of path difference why bright and dark lines are formed on the screen.

Answer 4

Constructive interference produces bright lines AND destructive interference produces dark lines
In phase for bright AND antiphase for dark
Path difference is a whole number of wavelengths for bright
Path difference is an odd number of half wavelengths for dark

Question 5

Describe the behaviour of cast iron

Answer 5

Brittle (no plastic region)
Elastic (returns to original length when load removed; linear graph; Hooke’s Law obeyed)

Question 6

Describe the material behaviour of copper

Answer 6

Ductile (can be formed into a wire)
Initially elastic
Plastic where it stretches more with little increase in stress
Doesn’t return to original length when load removed
Necking at the end

Question 7

Describe the material behaviour of polythene

Answer 7

Easy to deform/deformed with little force
Plastic
Ductile
Polymeric

Question 8

Describe in detail how the Young Modulus of a metal can be determined

Answer 8

Area: micrometer for diameter
Original length: metre rule
Force: masses (mass balance or m x g)
Extension: marker on wire and mm scale

Length of wire greater than 1m
Repeat for number of loads
Measure diameter in several places
Measure original length to marker
Marker put nearer to pulley

Plot a graph