How We See

  • How we see things is due to light reflecting into our eyes.
  • Luminous objects produce light =reflects off non luminous objects = reflected light goes into our eyes


    • camera =


    • camera.

    • Light travels in a straight line from the object to the tracing paper screen through the pinhole.
    • As pinhole is small = only one ray gets in from each point on the object.
    • Image of the object is upside down and crossed over as the light rays cross over inside the camera.
    • Lenses = focus light = refracts light

Measuring Current and Potential Difference

  • Convex lens = bulges outwards = causes light rays to converge (move together ) to a focus
  • Human eye = cornea is a transparent window with convex shape = does most of the eyes focusing.
  • Convex lens behind the cornea = changes shape = focuses light from objects at varying distances
  • Iris = coloured part of the eye = controls the amount of light entering the eye
  • Retina = where images are formed = retina cells are photo-sensitive
  • Energy is carried by light waves
  • Absorber = anything which absorbs this energy
  • Energy is transferred to the absorber when energy hits it
  • Light waves hit retina cell = causes chemical and electrical changes = sends signals to brain
  • Digital camera = light causes sensor to generate an electrical charge = changes in charge read by computer = image

How long have you…? (present perfect 4) Exercises




Use the information given to create questions beginning with ‘How long…?’

• It is snowing.

• The weather is shining.

• John and Kate are married.

• My brother has gone on holiday.

• My aunty and uncle live in Canada.

• My sister is a teacher.

• I work at the chemist.

• I’ve known Susan since I was a baby.

• Jonathan is learning to speak to Mandarin.




Fill in the missing gaps in the sentences using the present perfect (=has/have + past participle)

• I have known Kate a long time.

• My brother has been playing the piano he was 11 years old.

• My mum and dad on holiday to America. They

gone since last Sunday.

• I Ben and Emma since primary school.

We to the same primary and secondary school.

• My sister learning to speak French because she
is going to France next month.



Use the appropriate words in the missing gaps.

have you lived       lives      to

has been       works        have known

I have bought       have worked.

• My sister in Spain. She is studying Spanish

with her friend Rosie. I Rosie since I was 5.

• Spencer like with Jamie. They have worked

together for 2 years.

• How long in Australia?

• a new dress for prom.

• He to Thorpe park.



Challenge: Create 4 of your own questions beginning with ‘How long……?’








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“Every accomplishment starts 
With the decision to try.” Gail Dever

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