Laws/Definitions

Question 1

Newton’s 1st Law

Answer 1

An object will remain in its current state of motion, unless acted on by a resultant force. An object requires a resultant force to be able to accelerate.

Question 2

Newton’s 2nd Law

Answer 2

The sum of the forces acting on an object is equal to the rate of change of momentum of the object.

Or F=ma.

Question 3

Newton’s 3rd Law

Answer 3

Every action has an equal and opposite reaction. If an object exerts a force on another object, then the other object must exert a force back, that is opposite in direction and equal in magnitude.

Question 4

Ohm’s Law

Answer 4

The current and potential difference through an ohmic conductor held under constant physical conditions are directly proportional, with the constant of proportionality being resistance.

Question 5

Hooke’s Law

Answer 5

The extension of an elastic object will be directly proportional to the force applied to it up to the object’s limit of proportionality.

Question 6

Kirchhoff’s 1st (Current) Law

Answer 6

The current flowing into a node (or a junction) must be equal to the current flowing out of it. This is a consequence of charge conservation.

Question 7

Kirchhoff’s 2nd (Voltage) Law

Answer 7

In any complete loop within a circuit, the sum of all emf’s (cells/batteries) must equal the sum of all voltages across all components in the same loop. This law is a consequence of both charge conservation and the conservation of energy.

Question 8

Boyle’s Law

Answer 8

Pressure is inversely proportional to volume when at a constant temperature.

Question 9

Charles’ Law

Answer 9

Volume is directly proportional to absolute
temperature at a constant pressure.

Question 10

Pressure Law

Answer 10

Pressure is directly proportional to absolute temperature at a constant volume.

Question 11

Faraday’s Law

Answer 11

The magnitude of the induced emf is equal to the rate of change of flux linkage through the circuit.

Question 12

Kepler’s 3rd Law

Answer 12

The square of an object’s orbital period (T) is directly proportional to the cube of its orbital radius (r).

Question 13

Lenz’s Law

Answer 13

The direction of an induced emf/current when there is a change of flux linkage is such that it will oppose the change that caused it.

Question 14

Snell’s Law

Answer 14

N1sin(x)=N2sin(x)

Question 15

Strange Particles

Answer 15

Particles that are produced through the strong interaction but decay through the weak interaction.

Question 16

Modal Dispersion

Answer 16

Waves enter an optical fibre at slightly different angles, meaning the distance each beam has to travel is slightly different. This leads to the beams reaching the end at different times and so causes pulse broadening.

Question 17

Material Dispersion

Answer 17

Waves of different wavelengths travel at slightly different speeds through an optical fibre and so reach the end of the fibre at slightly different times, causing pulse broadening. The use of monochromatic light fixes this.

Question 18

Specific Heat Capacity

Answer 18

The amount of energy required to increase the temperature of 1kg of a substance by 1 Kelvin.

Question 19

Specific Latent Heat

Answer 19

The amount of energy required to change the state of 1kg of a substance without a change of temperature.

Question 20

Motor Effect

Answer 20

When a current-carrying wire is placed within a magnetic field (non-parallel to the field lines) and experiences a force perpendicular to both the wire and the field lines.

Question 21

Synchronous Orbit

Answer 21

An orbit in which the period of the orbit is equal to the rotational period of the object that it is orbiting.

Question 22

Time Constant

Answer 22

The time taken for a capacitor to discharge to 37% (e^-​1)​ of its initial charge. The time constant is equal to the product of the capacitance and the resistance of the fixed resistor (that the capacitor is being discharged through).

Question 23

Magnetic Flux, ​φ​

Answer 23

A value which describes the magnetic field or field lines passing through an area. It is the product of magnetic flux density and the perpendicular area it passes through.

Question 24

Magnetic Flux Density, B

Answer 24

The force per unit current per unit length on a current-carrying wire placed at 90o to the field lines. Sometimes also referred to as the magnetic field strength.

Question 25

Magnetic Flux Linkage, N​φ​

Answer 25

The magnetic flux multiplied by the number of turns, N, of the coil.

Question 26

Progressive Wave

Answer 26

One that transfers energy from one point to another, without transferring matter.

Question 27

Define SHM

Answer 27

Motion where the acceleration of an object is directly proportional, and in the opposite direction, to its displacement.

Question 28

Assumptions for Ideal Gas (RAVED mnemonic)

Answer 28

Random motion (Brownian Motion).
No attractive forces.
Negligible volume of particles compared to gas.
Elastic collisions.
Duration of collisions is negligible compared to the time between them.

Question 29

Isothermic

Answer 29

Constant temperature

Question 30

Tesla

Answer 30

The magnetic flux density for which a wire of 1m carrying 1A experiences a force of 1N when perpendicular to the magnetic field.

Question 31

How is high level radioactive waste treated?

Answer 31

• Highly radioactive consists of spent fuel rods.
• Initially placed in cooling ponds to cool it down for a number of years as it’s very hot.
• Uranium is separated and recycled.
• It also must be handled remotely to avoid human contact.
• High level waste is vitrified (solidified into glass) so it doesn’t leak when placed in steel barrels, which are stable, as it’ll be radioactive for hundreds of thousands of years.
• Then it’s stored DEEP underground because it’s geologically stable down there.
• transporting it presents potential danger to public so waste is enclosed in extra thick and strong casings.

Question 32

What is an Eddy Current?

Answer 32

As the Primary Coil’s magnetic field induces emf in the secondary coil, it also induces emf and therefore mini currents in the iron core, which are eddy currents.