2021

• What is mean by elastically deformed

  The spring will return to its original length when the force is removed.
• equation linked oty extension,force, spring constant

  F=ke
• vector quanitties

  -velocity

  -acceleration
• vector quantity

  a quantity with both magnitude and direction
• vector quantity

  displacement
• equation linked to acceleration, mass , and resultant force

  F=ma
• What is the advantage of taking repeat readings and then calculating a mean

  reduces the effect of random errors
• How does the depth of water affect the wavelength of the wave if the frequency is constant

  deeper water means longer wavelength because increases and f is constant
• Where is the magnetic field of the magnet the strongest

  at the poles
• Why is an electromagnet used instead of a permanent magnet

  electromagnet is easy to demagnetise, so easy to remove separated metal.
• Which metal is attracted to the electromagnet

  -cobalt

  -nickel

  -iron

  -steel
• magnetic flux density unit

  tesla or T
• Flemings left-hand rule

  Shahadah finger -direction of magnetic field

  middle finger- direction of current

  thumb-direction of force
• Infrared has a range of wavelengths

  from 700nm to 1mm
• Which part of the electromagnetic spectrum would have waves with a wavelength of $6.5\times10^{-7}$m?


  visible light
• Describe a method to determine the extension of the spring.[2 marks]

  • Measure the original length of the spring and the extended length of the spring with a ruler.
  • Extension = extended length − original length.
• Describe how the frequency and wavelength of the water waves in the ripple tank can be measured accurately.[4 marks]

  Wavelength:

  • Place a metre rule at the side of the screen perpendicular to the wave fronts.
  • Take a photograph of the shadow on the screen.
  • Count the number of complete waves on the screen.
  • Determine the wavelength by dividing the total length by the number of waves.

  Frequency:

  • Count the number of waves that pass a given point.
  • Time how long it takes using a stopwatch.
  • Use: frequency = number of waves ÷ time taken.
• How does Figure 4 show that the strength of the magnetic field is not the same at all places?[1 mark]The distance between the field lines varies.

  
• Give two ways the force exerted by the electromagnet on a piece of iron or steel could be increased.[2 marks]

  1. Increase the current in the coil of the electromagnet.
  2. Bring the electromagnet closer to the pieces of iron or steel.
• Explain why the infrared camera is able to show that parts of the hand are at different temperatures.[2 marks]

  Different temperatures emit different intensities of infrared, which are represented (on the infrared camera) as different shades/colours.
• Compare the potential risks to a patient of using X-rays and gamma rays for medical imaging.[4 marks]

  • Both are ionising radiation, so there is some risk of cancer.
  • The whole body is irradiated by gamma rays, whereas when an X-ray is taken, only part of the body is exposed.
  • Exposure time for gamma rays is longer.
• Explain why using tungsten as the metal target enables the X-ray machine to be more powerful.[3 marks]

  Some of the energy of the electrons causes heating, therefore increasing the temperature, so using tungsten allows more electrons to be collided per second than using any other metal.
• An aeroplane accelerates from a low speed to a high speed with the engines at maximum power.Explain why the acceleration is not constant.[5 marks]

  • At maximum power, the forward force of the engines is constant.
  • As it accelerates, the air resistance increases.
  • Resultant force = force from the engines − air resistance.
  • Thus, resultant force decreases.
  • Acceleration is directly proportional to resultant force.