Test 5 completed Flashcards
State the principle of conservation of energy.
energy cannot be created or destroyed energy can only be transferred
Define the unit kWh.
energy transferred in one hour at a rate of transfer of 1 kW
Calculate the energy produced by the wind
energy= power x time
State and explain the two ways that thermal energy is conducted in a metal.
Free electrons collide with distant particles. Lattice vibrations transfer energy to neighbouring particles.
State two ways in which boiling differs from evaporation.
occurs at fixed temperature and takes place throughout the liquid
Light enters the semilunar block, path?
Straight side is a mirror
We can see light from the Sun but we cannot hear any sound from it.
State the reason for this.
Sound needs a medium to travel through
Convert seconds to milliseconds
x1000
Define potential difference (p.d.).
work done in passing charge across a component
(work done per unit charge)
State the equation which defines electromotive force (e.m.f.) E.
E=W/Q
Circuit symbol for d.c power supply
Space with two circles, showing which is positive and negative
State and explain what happens to the coil as it reaches the vertical position.
Coil stops. The turning effect is zero. Past vertical, the turning effect changes direction.
Explain the effects of the split‐ring commutator and the brushes on the action of the motor.
Split-ring commutators reverse the current every half-turn, so that the coil rotates continuously. Brushes ensure the current is maintained
Explain what is meant by nuclear fission.
A large unstable nucleus splits into smaller nuclei and large amount of energy is released
Explain what is meant by redshift.
Wavelength increases and occurs when galaxies are moving away from Earth
