PHYSICS IGCSE CIE EXAM Q

SCALAR QUANTITIES INVOLVE MAGNITUDE

Temperature

Speed

Mass

Distance

VECTOR QUANTITIES INVOLVE MAGNITUDE AND DIRECTION

Gravitational field strength

Force

Weight

Velocity

WHAT IS SPECIFIC HEAT CAPACITY

The amount of heat needed per 1KG of mass to increase temperature by 1*C

WHAT IS SPECIFIC LATENT CAPACITY

The amount of heat needed per 1KG of mass to change state

PROPERTIES OF A THERMOMETER

→ Can only measure 100*C

→ Mercury expands when heated up

→ Additional volume increases accuracy of temperature measurement

PROCESS OF CONDENSATION

Liquid particles gain energy and move faster and break free from the liquid into the air. In boiling, they escape in forms of bubbles.

PROCESS OF CONDUCTION

Solid particles are close together, and when heated vibrate in place and gain more energy. This energetic particle then vibrates against neighbouring particles which then spreads throughout the whole solid.

WHAT IS THE CONVECTION CURRENT

Warmer fluid is less dense and rises

Cooler fluid is denser and sinks

Distributing heat through the fluid

THERMAL EXPANSION EG.

→ Railway lines

→ Thermometers

→ Power lines

PROCESS OF LIQUID EXPANSION

When a liquid is heated, its particles gain energy and move faster. This increased movement causes the particles to spread out and take up more space, making the liquid expand.

PROPERTIES OF TRANSVERSE WAVE

→ Seismic s-wave

→ Vibration is 90* to propagation

→ Electromagnetic wave

PROPERTIES OF LONGITUDINAL WAVE

→ Seismic P-wave

→ Vibration is parallel to propagation

→ Sound wave

ELECTROMAGNETIC SPECTRUM

Red has the longest wavelength and the lowest frequency

Violet has the shortest wavelength and the highest frequency

SPEED OF LIGHT IN: AIR, WATER, GLASS

Air: 3.0×10^8

Water: 2.25×10^8

Glass: 2.0×10^8

USES OF ELECTROMAGNETIC SPECTRUM

Radio waves: radio and television transmissions & RFID

Microwaves: satellite television, mobile phones, microwave oven

Infrared: short range communications, intruder alarms, thermal imaging, optical fibres

Visible light: vision, photography, illumination

Ultraviolet: security marking, detecting fake bank notes, sterilising water

X-rays: medical scanning, security scanners

Gamma rays: sterilising food & medical equipment, detection & treatment of cancer

HOW DOES AN OPTICAL FIBRE WORK

It uses the principle of total internal reflection to transmit data efficiently through light signals, typically using infrared light.

PROPERTIES OF DISCRETE SIGNALS

→ Binary

→ Higher transmission rates

→ Digital data, internet signals, computer memory

PROPERTIES OF ANALOG SIGNALS

→ Continuous

→ Limited by signal degradation over distance

→ Audio, television, older telephone systems

LENZ’S LAW

The direction of the induced current opposes the change of the flux that creates it

HOW IS CURRENT PRODUCED IN THE SECONDARY COIL IN A TRANSFORMER

When a.c flows through the primary coil, it creates an alternating magnetic field; this then induces a current in the secondary coil through electromagnetic induction.

FLEMING LEFT HAND AND RIGHT HAND RULE

IONISING & PENETRATING POWER OF ELECTROMAGNETIC WAVE

a-particle: very strong & very weak (paper block)

b-particle: medium & medium (aluminium foil block)

y-radiation: very weak & very strong (lead block)

USES OF ELECTROMAGNETIC WAVE

a-particles:

→ smoke detectors, able to ionise the air—making smoke flow slower than usual which triggers the alarm

→ less dangerous unless source is inhaled or ingested

b-particles:

→ used to measure thickness of material

y-rays:

→ high penetrating power allows killing of bacteria and harmful cells

LIFE CYCLE OF A STAR

1) A star is formed from interstellar clouds of gas and dust that contain hydrogen

2) A protostar is an interstellar cloud collapsing and increasing in temperature as a result of its internal gravitational attraction

3) A protostar becomes a stable star when the inward force of gravitational attraction is balanced by an outward force due to the high temperature in the centre of the star

4) Most stars expand to form red giants & massive stars expand to form red supergiants when most of the hydrogen in the centre of the star → to helium

5) A red giant from a less massive star forms a planetary nebula with a white dwarf star at its centre

6) A red supergiant explodes as a supernova, forming a nebula containing hydrogen + new heavier elements, leaving behind a neutron star or a black hole at its centre

7) The nebula from a supernova may form new stars with orbiting planets

DEFINITION OF REDSHIFT

An increase in the observed wavelength of electromagnetic radiation emitted from receding stars and galaxies

DEFINITION OF HUBBLE CONSTANT

The ratio of the speed at which the galaxy is moving away from the Earth to its distance from the Earth

H = v/d & 2.2 × 10^–18 per second

This is evidence for the idea that all the matter in the Universe was present at a single point