AQA a level physics paper 1 Practice Questions And Answers Verified 100% Correct

AQA a level physics paper 1 Practice Questions And Answers Verified 100% Correct How does TIR transmit information in an optical fibre? (2+ diagram) - ANSWER Core has higher refractive index than cladding (1) when incident light at a greater angle than critical angle of cladding TIR occurs (2) Observations of a polarisation filter rotation? ("What observations could be made when the filter in rotated through 360˚?") - ANSWER Variation in intensity between maxima and minima (light and dark) (1) Two maxima and Two minima within 360 (1) define moment of a force (2) - ANSWER force x perpendicular distance around a pivot (1) between force and pivot (2) define center of gravity - ANSWER the point in a body (1) where the weight of an object appears to act (1) state principle of moments - ANSWER for a body in equilibrium (1) the sum of clockwise moments about a point (1) is equal to the sum of anticlockwise moments state the principle of conservation of momentum - ANSWER total momentum before = total momentum after (1) in an isolated system (no external force) state the relationship between the force acting on a body and the momentum of the body - ANSWER force proportional to rate of change of momentum define center of mass - ANSWER the point in the body through which the mass appears to act conditions for equilibrium - ANSWER resultant force is 0 (1) resultant torque is 0 (1) difference between scalar and vector - ANSWER vector has magnitude and direction scalar only has magnitude definition of elastic limit - ANSWER maximum force/load which can be applied to the object without it being permanently deformed define hookes law - ANSWER Extension is proportional to the applied force up to limit of proportionality (1) as long as extension is small (1) newton's first law - ANSWER object in motion remains in motion and object stationary remains stationary till external force acts on it newton's second law - ANSWER f=ma newton's third law - ANSWER every action has an equal and oppisite reaction define yield stress of a material - ANSWER force per unit area (1) at which material permanently deformed (1) for no/small increase in force define density of a material - ANSWER mass per unit volume explain what is meant by spring constant (k) - ANSWER force divided by extention state what is meant by a superconductor (2) - ANSWER conductor which has 0 resistance (1) at critical temperature (1) state what is meant by the emf of a battery (1) - ANSWER energy changed to electrical energy per unit charge define potential difference - ANSWER work done per unit charge explain why the use of superconductors would improve the efficiency of power stations and hence reduce carbon dioxide emissions - ANSWER less energy lost (In conducting wires) (1) less fuel needed (1) explain what is meant by a potential divider - ANSWER a combination of resistors across a voltage source to produce a required pd state what is meant by 'non-ohmic' - ANSWER resistance not constant (V not directly proportional to I) example of non-ohmic conductor - ANSWER filament lamp/LDR/thermistor Advantage of using a stranded cable rather than a solid cable of the same cross- sectional area - ANSWER larger surface area so better heat dissipation Explain what is meant by resonance (4) - ANSWER driving frequency = natura l frequency (1) vibrations of large amplitude produced (1) max energy transferred at resonance (1) phase difference between driver and oscillator is 90 degrees (pi/2 rads) Explain what is meant by forced vibrations (5) - ANSWER forced vibrations = periodic force applied (1) frequency determined by as frequency of oscillator (1) phase difference is 180 degrees (pi rads) (1) frequency of driver frequency of oscillator (1) amplitude small at high frequency and vice versa explain what is meant by damping - ANSWER removes energy from oscillating system (OR when force opposes motion of oscillator) how does damping affect resonance - ANSWER reduces amplitude at resonant frequency name two types of potential energy involved when a mass-spring system performs vertical SHM - ANSWER elastic potential and gravitational potential describe what is meant by the period of an oscilation - ANSWER time taken for one complete oscillation state conditions necessary for SHM (2) - ANSWER acceleration proportional to displacement (1) directed towards mean position A particle that moves uniformly in a circular path is accelerating yet moving at a constant speed. Explain this statement by reference to the physical principles involved (4) - ANSWER speed scalar velocity vector (1) direction changes continuously (1) velocity changes (1) acceleration is rate of change of velocity What is meant by damping - ANSWER When force opposes motion What is meant by work function (2) - ANSWER Minimum energy required by an electron to escape from (1) a metal surface (1) What is meant by ionisation energy? (2) - ANSWER Minimum energy required to remove an electron from an atom (1) from the ground state (1) Why do emitted electrons have a kinetic energy that varies up to a maximum value? (4)