Questions

Question 1

What happens to the brightness of a lamp when a variable resistor is connected in parallel?

Answer 1

(resistance increases)
- Reduces current in battery
- Reduces lost volts and increases terminal p.d.
- Lamp becomes brighter

Question 2

What properties/stress-strain characteristics
should a material used for bungee jumping have?

Answer 2

• Large Tensile strain for a given stress.
• ∵ Time taken to come to rest lengthens

Question 3

Why would a wire no longer return to its’ original shape after usage?

Answer 3

wire is stretched beyond elastic limit/ Deform plastically.
- Results in permanent deformation

Question 4

How is a stationary wave formed and why can stationary waves only be certain frequencies?

Answer 4

• wave travels along string and is reflected at each end
• these two coherent waves superpose resulting in the formation of nodes & anti-nodes.
• only certain frequencies because fixed ends have to be nodes

Question 5

What happens to the brightness of a lamp when a variable resistor is connected in series?

Answer 5

• resistance increases
• reduces current through lamp
• lamp dimmer

Question 6

Explain why resistivity of a wire changes with temperature

Answer 6

• Resistance/resistivity increases with increasing temperature.
• (lattice) ions vibrate with greater amplitude
• rate of movement of charge carriers/electrons (along wire)
  is reduced. (for given p.d.)

Question 7

• What properties does this material have and how does this graph show that?

Answer 7

• Brittle
  ↳ little to no plastic behaviour
• Stiff
  ↳high Young Modulus
  ∵ steep gradient

Question 8

What is meant by an EMF of _V for a battery?

Answer 8

• The amount of energy transferred from chemical energy to electrical energy (for every coloumb of charge).
• _J of energy per coloumb of charge.

Question 9

At the instance a free falling object has been caught what is the direction of its velocity, acceleration and pull force?

Answer 9

• the velocity is downwards because the object is falling toward the ground
• The net force is upwards
• the system (object) accelerates in the same direction as the net force so the boxes acceleration is upwards
• since the object’s velocity and acceleration are in opposite directions, the box slows down.