2018

• Explain why the total positive charge in every atom of an element is always the same.

  Answer:

  • Positive charge is provided by protons.
  • Every atom of the same element contains the same number of protons.
• Plan an experiment that would allow the student to determine the density of the object.

  Answer:

  • Measure mass
  • Use a top pan balance or scales
  • First fill a measuring cylinder with water
  • Measure initial volume
  • Place object in water
  • Measure final volume
  • Volume of object = final volume - initial volume
  • Fill a eureka can with water
  • Water level with spout
  • Place object in water
  • Collect displaced water
  • Measuring cylinder used to determine volume of displaced water
  • Use:density=massvolume\text{density} = \frac{\text{mass}}{\text{volume}}density=volumemass​
• What is an alpha particle?

  Answer:✔ 2 charged particles and 2 neutral particles.
• Which statement about beta radiation is true?

  Answer:✔ It is the type of radiation with a negative charge.
• Which statement about gamma radiation is true?

  Answer:✔ It has a very long range in air.
• Explain how the readings on both meters change when the environmental conditions change.

  Answer:

  • Resistance of LDR changes when light intensity changes
  • When light intensity increases the resistance of LDR decreases
  • Overall resistance of circuit decreases
  • p.d. across the total resistance remains unchanged
  • Current in ammeter increases
  • p.d. across fixed resistor increases
  • p.d. across LDR decreases
  • Reading on the voltmeter decreases
  • p.d. is shared between the components in series
  • The lower the resistance of the LDR, the smaller the share of the p.d.
  • Reading on the voltmeter decreases