Radioactivity and Particles + OSCILLOSCOPE + STATIC ELECTRICITY

Question 1

What is needed for fusion to occur? [3]

Answer 1

• Presence of hydrogen isotopes
• Extremely high temperatures(10^7C to overcome the repulsion between protons as they will have high KE and be travelling at high speeds)
• Very high pressure to increase the number of collisions and overcome electrostatic repulsion between protons

Question 2

What are the fuel rods made from in Nuclear reactors and what are they for?

Answer 2

• Made from Uranium
• Where energy comes from and fission occurs

Question 3

What are the control rods made from and what are they for?

Answer 3

• Made from Boron
• Form a barrier between fuel rods, absorbing neutrons and reducing reaction rate

Question 4

What are moderators made from and what are they for? [3]

Answer 4

• Made from water surrounding the rods
• Reduces the velocity of neutrons so they can be absorbed for further fission
• So that they are in thermal equilibrium to ensure they react efficiently with Uranium fuel

Question 5

Why and how is shielding used in Nuclear Reactors?

Answer 5

• Absorbs hazardous radiation such as the radioactive daughter nuclei and neutrons
• Done by covering the reactor in steel and concrete, up to 2m thick

Question 6

How does an oscilloscope work? [4]

Answer 6

• A microphone is plugged into the oscilloscope, so the longtitudinal wave is shown on the screen as if it were a transverse wave
• The time base(x-axis) is used to measure the time period of the wave
• The height of the wave, measured from the centre of the screen, is used to measure the amplitude of a wave.
• The number of entire waves that appears on the whole screen is the frequency of the wave

Question 7

Hint: Think like a mark scheme

How is an oscilloscope used to measure the frequency of a wave? [3]

Answer 7

• Adjust the oscilloscope to get a steady trace, by freezing the screen
• Adjust the time base to display at least one cycle
• Evaluate the number of squares for a full cycle, and multiply it by the time base

Question 8

How do photocopiers work?

Answer 8

• An image of the document is placed onto the positively charged copying plate
• The plate loses its charge in the light areas and keeps its charge in the dark areas
• A negatively charged black toner powder is applied to the plate and sticks to the positively charged parts
• The toner is then transferred to a new blank sheet of white paper
• The paper is heated to make sure the powder sticks, and the photocopy is now made

Inkjet printers work in a similar way, but instead of the black toner powder, a small jet of coloured ink is negatively charged and attracted to the correct place on the page.