B1- Core Science Concepts (Physics) Flashcards
What is the equation to calculate Charge?
Q=IT
Charge = Current X Time
(Q-coulombs - C) (I - Current - A) (T - Seconds - s)
What is the equation relating to Ohms Law?
V=IR
voltage=current x resistance
(V - Voltage- Volts )(I - Current- Amps) (R-Resistance - Ohms Ω)
How do you calculate total resistance in a series and parallel circuit?
series: sum of the individual resistors
parallel: 1/Rt=1/R1+1/R2
What is the difference between alternating and direct current?
Direct: the direction of the current of the voltage is always constant
Alternating: the direction of the current is always switched periodically, and the voltage is also switched
constantly changes direction
Properties of mains electricity in the UK
- AC
- PD ensures electricity is supplied to residences and businesses at 230V
- Generated at a frequency of 50Hz
Where is the magnetic force the strongest on a magnet?
- N/S magnetic poles are where the magnetic forces are strongest
Give an example of a non-contact force
- Attraction/repulsion of magnets in close proximity - attraction and repulsion between magnetic poles are examples of non-contact forces
The difference between permanent and induced magnets
Permanent magnet produces its own magnetic field.
Induced magnet is a material that becomes a magnet when it is placed in a magnetic field.
Uses of permanent and temporary magnetic materials (e.g. Iron, steel, cobalt, nickel)
p: Horseshoe and bar magnets
MRI
t: paperclips, temporary electromagnets, phones, speakers
What is the shape and direction of a magnetic field around bar magnets?
The relationship between the strength of the field and concentration of lines?
closed lines with arrowhead going from N to S
magnetic field is stronger at the poles and where the field lines are concentrated
How a magnetic field is produced by the flow of current through conducting wire
what is the relationship between the strength of the field, size of current and distance to the wire?
When a current flows in a wire, it creates a circular magnetic field around the wire.
strength of field - bigger/closer with magnetic field
size of current - bigger field
distance to wire - the closer, the stronger the wire
Portative vs Tractive
A portative electromagnet is one designed to hold the material in place.
A tractive electromagnet applies a force and moves something.
Principles of electromagnetic induction
Is where a conductor is put in a particular position and magnetic field keeps varying or magnetic field is stationary and a conductor is moving - producing voltage
Principles of the motor effect
motor effect is when a current carrying wire’s magnetic field interacts with the magnetic field around it, resulting in a force being exerted on it, causing it to move.
current flow in a conductor kept in an external magnetic field causes a deflecting force on the electrons in the conductor, which in turn causes the deflection of the conductor itself.
Application of electromagnets in electric and electromechanical devices
- Transformers
- Induction heating
- MRI machines
- Electric bells and buzzers
Definition of a wave
Transfer of energy, not matter
Equation for wave speed
v=fλ Wave speed(m/s) = frequency(Hz) x wavelength(m)
Properties of Transverse waves
- Oscillations perpendicular to the direction of travel
- Can travel through a vacuum
- Peaks and troughs
- Visible, radio, x-rays, and microwaves
Properties of Longitudinal waves
- Oscillations are parallel
- Cannot travel through a vacuum
- Compression and rarefactions
- Sound waves and earthquakes
Uses of different waves
- Communication (for example radio waves)
- Medical uses (for example X-rays, gamma rays for cancer treatment and sterilisation, ultrasound in scanning and cleaning computer equipment)
- Food processing (for example infrared heating and microwave heating)
Types and properties of ionising radiation
Alpha:
- high ionising but low penetrating power
- Range is 1 to 2 centimetres of air
Beta:
- medium ionising and penetrating power
- Range is approximately 15 centimetres of air
Gamma:
- Low ionising and high penetrating power
- Range is many kilometres of air
Define half life
The time taken for half the unstable nuclei in a sample to decay
Define count rate
The number of decays recorded each second
The main types of radioactive decay in relation to unstable nuclei
- An alpha particle - consists of 2 neutrons and 2 protons and is equivalent to a helium nucleus
- Beta particle - a high speed electron ejected from the nucleus as a neutron turns into a proton
- Gamma ray - electromagnetic radiation from the nucleus
