maddyhelps

Science 9

Science 9 · Worksheets

Mixed review · Electricity and space

Ten questions of mixed difficulty, covering Electricity, Space exploration. Print it, or work through it on screen — the answer key starts on its own page.

All worksheets

Mixed review · Electricity and space

Science 9 · maddyhelps.com

Name
Date
Score
/ 10

Circle the best answer for each question. Show your work in the space provided.

  1. To measure the voltage across a lamp, a voltmeter must be connected

    1. a) between the switch and the lamp
    2. b) in parallel, across the lamp
    3. c) in series, next to the lamp
    4. d) in series with the battery

  2. A student's model generator, a coil turned by hand between two magnets, lights a small bulb only dimly. Which change would most likely make the bulb brighter?

    1. a) Using fewer turns of wire
    2. b) Turning the coil faster
    3. c) Using weaker magnets
    4. d) Turning the coil more slowly

  3. Canada's RADARSAT satellites can take images of Earth through cloud and in the dark because they

    1. a) fly low enough to pass beneath the clouds
    2. b) send out radar signals and record the echoes
    3. c) take images only in the summer months
    4. d) use ordinary cameras with lenses large enough to see through cloud

  4. A star chart says a planet will be at altitude 30° and azimuth 90°. Where should you look?

    1. a) East, one third of the way down from overhead
    2. b) West, one third of the way up from the horizon
    3. c) East, one third of the way up from the horizon
    4. d) North, one third of the way up from the horizon

  5. A hair dryer draws 10 A from a 120 V outlet. Its power is

    1. a) 12 W
    2. b) 1200 W
    3. c) 130 W
    4. d) 0.083 W

  6. A light-year is a measure of

    1. a) brightness: how much light a star gives off
    2. b) speed: how fast light moves through space
    3. c) distance: how far light travels in one year
    4. d) time: how long one year lasts out in space

  7. Two bulbs are connected in series to a battery. An ammeter placed before the first bulb reads 0.4 A. An ammeter placed after the second bulb will read

    1. a) 0.8 A
    2. b) 0 A
    3. c) 0.4 A
    4. d) 0.2 A

  8. Radio signals travel at the speed of light, which covers 1 AU in about 8.3 minutes. A probe at Saturn, 9.5 AU from the Sun, radios Earth while Earth is directly between Saturn and the Sun. About how long does the signal take?

    1. a) about 71 minutes
    2. b) about 79 minutes
    3. c) about 1 minute
    4. d) about 87 minutes

  9. A remote northern community makes its electricity with diesel generators and is deciding whether to add a solar farm. Which fact most strongly supports building it?

    1. a) Solar panels are a newer kind of technology
    2. b) Diesel generators have powered the town reliably for many years
    3. c) It would cut the diesel that must be trucked or flown in
    4. d) Solar panels make electricity only in daylight

  10. Compared with the Sun, a star with 20 times the Sun's mass will

    1. a) last longer and end quietly as a white dwarf
    2. b) last longer, since it has more fuel to burn
    3. c) use its fuel faster and end in a supernova
    4. d) use its fuel faster and end as a white dwarf

Answer key · Mixed review · Electricity and space

Science 9 · maddyhelps.com

  1. b) in parallel, across the lamp — A voltmeter compares the energy carried by the charge on either side of the lamp, so its two leads go on either side of it, in parallel. It is the ammeter that goes in series, because it has to count the current flowing through.
  2. b) Turning the coil faster — A generator makes current by moving wire through a magnetic field, and the faster the motion, the greater the voltage. More turns of wire and stronger magnets also help; fewer turns and weaker magnets do the opposite.
  3. b) send out radar signals and record the echoes — Radar sends out its own microwaves and measures what bounces back, so it needs neither sunlight nor clear skies. Ordinary cameras record reflected sunlight, which is why they see nothing useful through cloud or at night.
  4. c) East, one third of the way up from the horizon — Azimuth is the compass direction measured clockwise from north, so 90° is east. Altitude is the angle up from the horizon, and 30° is a third of the way to the point straight overhead at 90°.
  5. b) 1200 W — P = IV = 10 × 120 = 1200 W, or 1.2 kW. Dividing instead gives 12 W, far too little to heat air; checking that the answer is sensible for a heating appliance catches the slip.
  6. c) distance: how far light travels in one year — Despite the word year, a light-year is a distance, about 9.5 trillion km. A star 4 light-years away is one whose light took 4 years to reach us, so we see it as it was then.
  7. c) 0.4 A — Current is the flow of charge, and in a series circuit the same charge passes through every part, so the current is the same everywhere. The bulbs take energy from the charge, not the charge itself: current is not used up.
  8. a) about 71 minutes — With Earth between them, the gap is 9.5 − 1 = 8.5 AU, and 8.5 × 8.3 ≈ 71 minutes. Using 9.5 AU forgets that Earth is already 1 AU from the Sun, and adding the 1 AU puts Earth on the far side of the Sun instead.
  9. c) It would cut the diesel that must be trucked or flown in — Less fuel to buy and haul is a real saving in cost and pollution, so it is evidence for the solar farm. Daylight-only output is true but argues against it, and being newer is not a benefit by itself.
  10. c) use its fuel faster and end in a supernova — A massive star has more fuel but burns it far faster, so it lives millions of years instead of billions. At the end its core collapses and it explodes as a supernova, leaving a neutron star or a black hole: mass decides the ending.