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Sight and Optics
Electricity and Magnetism
Fields and Forces and Mechanics
Going Green! (energy)
Thermal and Nuclear
100
Which of the following electromagnetic waves has a frequency greater than that of visible light? A. Ultraviolet B. Radio C. Microwaves D. Infrared
What is Ultraviolet
100
A battery of internal resistance 2 Ω is connected to an external resistance of 10 Ω. The current is 0.5A, what is the emf of the battery?
What is 6V
100
A spherical planet of uniform density has three times the mass of the Earth and twice the average radius. The magnitude of the gravitational field strength at the surface of the Earth is g. What is the gravitational field strength at the surface of the planet?
What is 3/4g
100
What is the phenomenon that best explains why greenhouse gases absorb infrared radiation?
What is Resonance
100
What is the unit of surface heat capacity?
What is J m^−2 K^−1.
200
State the Rayleigh criterion.
What is What is for two images (of two objects) just to be distinguished/to be seen as separate images; maximum of one diffraction pattern must lie on first minimum of second;
200
One electronvolt is equal to A. 1 6 10 19 . × − C. B. 1 6 10 19 . × − J. C. 1 6 10 19 . × − V. D. 1 6 10 19 . × − W
What is B. 1.6 x 10 19 . x - J
200
A spacecraft travels away from Earth in a straight line with its motors shut down. At one instant the speed of the spacecraft is 5.4 kms –1. After a time of 600 s, the speed is 5.1kms –1. The average gravitational field strength acting on the spacecraft during this time interval is
What is 5.0 x 10^-1 Nkg^-1
200
In which of the following places will the albedo be greatest? A. A forest B. A grassland C. An ocean D. A polar ice cap
What is A polar ice cap
200
The energy of the molecules of an ideal gas is
What is A. thermal only. B. thermal and potential. C. potential and kinetic. D. kinetic only
300
The standing wave has wavelength λ and frequency f. State and explain, with respect to a standing wave, what is represented by the product f  λ.
What is What is f λ is the speed of the wave; standing wave formed by interference of an incident and a reflected progressive wave; speed is the speed of this progressive wave;
300
A nuclear power station produces 10GW of electrical power. The power generated by the nuclear reactions in the core of the reactor is 25GW. The efficiency of the power station is A. 15%. B. 35%. C. 40%. D. 60%.
What is C. 40%
300
A stone attached to a string is moving in a horizontal circle. The constant speed of the stone is v. The diagram below shows the stone in two different positions, X and Y. Which of the following shows the direction of the change of velocity of the stone when moving from position X to position Y?
What is the northeast son.
300
A wind turbine produces a power P when the wind speed is v. Assuming that the efficiency of the turbine is constant, the best estimate for the power produced when the wind speed becomes 2v is
What is 8P
300
The design of a nuclear power station includes an electrical generator. The function of the generator is to convert
What is kinetic energy to electrical energy
400
A student measures the aperture of the iris of one of her eyes as 2.0mm in sunlight and 7.0mm in moonlight. The intensity at her eye of sunlight is 106 times greater than the intensity of moonlight. Determine the following ratio. power of light entering the eye in sunlight/ power of light entering the eye in moonlight
What is What is (i) power =area×intensity; ratio=(2.0/7.0)^2 X 10^6=8.0 X 10^4
400
Define the Electromotive force (emf) of a battery
What is the work done per unit charge in moving a quantity of charge completely around a circuit / the power delivered per unit current / work done per unit charge made available by a source;
400
The stone leaves her hand with a speed of 15ms at the instant her hand is 80m above the surface of the sea. Air resistance is negligible and the acceleration of free fall is 10ms. a) Calculate the maximum height reached by the stone as measured from the point where it is thrown b) Determine the time for the stone to reach the surface of the sea after leaving Lucy’s hand
a) 11m b) 5.8s
400
The intensity of the Sun’s radiation at the position of the Earth is approximately 1400W m−2 Suggest why the average power received per unit area of the Earth is 350W m−2 .
What is the solar radiation is captured by a disc of area 2 πR where R is the radius of the Earth; but is distributed (when averaged) over the entire Earth’s surface which has an area four times as large;
400
What is the mass of carbon-12 that contains the same number of atoms as 14g of silicon-28?
What is 6g
500
Suggest why your answer in (a)(i) indicates that the change in diameter of the iris is not the principal mechanism by which the eye is able to adjust to different light intensities.
What is What is if iris were to be the principal mechanism, then ratio would need to be about (7/2)^2 or (2/7)^2
500
Define electrical resistance of a conductor.
What is the ratio of the voltage (across) to the current in the conductor;
500
A bus is travelling at a constant speed of 6.2ms along a section of road that is inclined at an angle of 6.0? to the horizontal. a) State the value of the rate of change of momentum of the bus.
What is zero
500
Outline a mechanism by which part of the radiation radiated by the Earth’s surface is absorbed by greenhouse gases in the atmosphere.
What isthe Earth radiates radiation in the infrared region of the spectrum; the greenhouse gases have energy level differences (in their molecular energy levels) corresponding to infrared energies; and so the infrared photons are absorbed; or the Earth radiates photons of infrared frequency; the greenhouse gas molecules oscillate/vibrate with frequencies in the infrared region; and so because of resonance the photons are absorbed;
500
Surface X has a temperature T(sub)x and emissivity ε x. Surface Y has a temperature T(sub)y and emissivity ε y. The two surfaces emit radiation at the same rate. What is the ratio T(sub)x/ T(sub)y ?
What is (ε(sub)y/ε(sub)x)^1/4