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PHYSICS TEST 30/4/14

QUESTION MARKS

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FORMULA SHEET

density = mass/volume ρ = m/v

power = voltage x current P = V I

energy transfer = power x time E = P t

units used (kWh) = power (kW) x time (h) cost = units used x cost per unit

wave speed = frequency x wavelength c = λ f

speed = distance/time

Prefix Multiplier Prefix Multiplier

p 10­12 k 103

n 10­9 M 106

μ 10­6 G 109

m 10­3 T 1012

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1. Electricity can be generated via a number of different sources. a.) i.) Name TWO sources of renewable and TWO sources of non­renewable energy;

RENEWABLE: 1. ……………………. 2. ……………………. NON­RENEWABLE: 1. ……………………. 2. …………………….

[2] ii.) Give an advantage and disadvantage of using solar panels to generate electricity. …………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

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b.) In 1986 the Chernobyl power plant suffered from a meltdown, in which many kilograms of radioactive material were ejected into the atmosphere. The local area is still uninhabitable as a result. As a result, many people no longer trust nuclear power stations. i.) Explain why some people may think badly of nuclear power, and make a suggestion as to a better source of power generation: …………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

[4] ii.) The following table shows the maximum power output of a modern nuclear power station, the radioactive waste products produced, and the cost of running;

POWER WASTE COST (POWER + WASTE)

20MW 4kg £20,000

40MW 10kg £29,000

60MW 18kg £39,000

80MW 28kg £51,000

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The following table shows the power, waste, and costs for a modern solar power plant;

POWER WASTE COST (POWER + WASTE)

5MW 3kg £10,000

10MW 3.5kg £15,000

15MW 4.5kg £18,000

20MW 6kg £19,000 Compare the two sources of power generation in terms of;

Max power output Waste produced Cost of running Environmental effects

[QWC] ………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

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………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

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END OF QUESTION

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2. In the UK, power is generated and distributed via the National grid. a.) i.) Describe the national grid; ………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

[2] ii.) The diagram below shows a step­up transformer:

The input voltage is 30V, the output is 1,000 times bigger, and the output power is 10kW. Calculate the output current:

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[1]

ii.) Using an equation from page 2, and the fact that the transformer is 98% efficient, calculate the input power;

[3] iii.) State the purpose of a step­down transformer, and describe how the number of coils affects the voltage on either side; ……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

[4] b.) Esteban decides to monitor his power usage throughout the day. He records the results as shown below:

TELEVISION: 2,000W KETTLE: 750W COMPUTER: 1,400W

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i.) The computer draws 200W per hour, and its power supply has a voltage of 150V. Calculate:

1. The amount of time he used the computer

2. The current drawn.

[2] ii.) The cost per unit is 18p. Calculate how much it cost Esteban to use his computer.

[3]

END OF QUESTION

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DO NOT WRITE ON THIS PAGE

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3. Modern homes now come with insulation built­in. As a result of the saving provided by this, many owners of older houses have begun to upgrade their insulation. a.) Delyth decides looks up a number of costs for insulating her house:

ITEM TYPE Cost (£) Annual Saving (£)

WALLS No Insulation ­ ­

­ Rockwool 900 100

ROOF No Insulation ­ ­

­ Rockwool 800 200

WINDOWS Single­Glazing ­ ­

­ Double­Glazing 1,800 18 i.) Calculate the payback time for double­glazing:

[1]

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ii.) Delyth has £2,600 to spend. By calculating payback time and annual savings, give the best way for her to spend her money. ………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

[5] c.) Idi Amin pays £288 per year on gas, and £460 on electricity. He uses standard power­sources (gas etc.). i.) Suggest ONE method of generating electricity he could use: …………………………………………………………………………………… ii.) Upon using a new source of power, his gas bill changed to £200 per year. The method of power­supply cost him £3,200. How long will it take for the gas bill to pay back the cost?

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iii.) Suggest why the payback time could vary; …………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

[3]

END OF QUESTION

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4. In a lab some students conduct a number of experiments of the nature of waves. They test longitudinal and transverse wave. a.) i.) Draw a longitudinal and transverse wave, indicating clearly which one is longitudinal/transverse:

[2] ii.) The students fired a sound wave at an acoustically reflective surface. They measured the time it took for the sound to return. The Wall was 10m away from the students.

1. Calculate the time taken for the wave to return to the students, given that the speed of sound in air is 343 ms­1

2. Why might the time recorded be different to the time you just worked out? ………………………………………………………………………………………………………………………………………………

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iii.) The students then conducted a test using transverse waves. They opted to use light. Name the seven different types of light which make up the EM spectrum, in order of decreasing wavelengths;

1. ………………. 2. ………………. 3. ………………. 4. ………………. 5. ………………. 6. ………………. 7. ……………….

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iv.) They test the waves with varying frequencies by passing them through a chamber containing a gas, and detect it on the other side. They record the following results:

WAVE WAVELENGTH

A 220

B 298

C 315

1. Calculate the frequencies of waves A and C:

2. visible light has a wavelength range of 198­267. Suggest what kind of light wave B could be. ……………………………………………………………….

[2]

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c.) It is known that gamma­rays are highly dangerous due to their potential to ionise. Name the other kinds of ionising radiation, and give their penetration and effects on the human body; [QWC] ……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

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END OF QUESTION

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5. In industry, many polluting chemicals are used and these have adverse effects on the environment. a.) Explain the greenhouse effect: ………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………….

[3] b.) i.) Large buildings often have trouble with heating.

1. Describe convection; ………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

2. Why would this not be sufficient to heat large, open spaces, such as a warehouse? ………………………………………………………………………………………………………………………………………………………………………………………………………………………

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ii.) A stream of hot water is pumped into a factory. At the start of this pump, the energy in the water is said to be 2,000J. During transport through pipes, it ends up with only 800J. What is the percentage efficiency of the pipes at keeping in energy?

[2] iii.) Suggest two ways by which one could reduce the energy/heat lost through the pipes; ……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

END OF QUESTION

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6.) Society today relies on the existence of satellites for communications. a.) i.) Jemimah describes the orbit of these satellites around earth:

“Communications satellites orbit the earth faster than it rotates, so that they can cover a large area quickly before signal is lost.” Explain why Jemimah is wrong; ……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

[3] ii.) Geosynchronous satellites orbit earth in the same period in which earth rotates. Why is this important for communications? ………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

[3] b.) BigSat has a geosynchronous orbit at 42,000 km. It sends signals to a station at your house’s conservatoory. The Venezuelan Government records the time taken. i.) Calculate the time taken:

[1] ii.) TinySat orbits Earth at an unknown height (due to the laziness of the SpaceX satellite management staff). It intercepts the signal sent from BigSat and responds. The time taken for signal to reach BigSat is 0.02 seconds.

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Calculate:

1. The distance between the two satellites

2. The time taken for a signal from TinySat to be sent to your hoouse given that it is relayed via BigSat

[3]

END OF PAPER