Turn over 5 6 A proton can be considered to be both a point charge and a point mass. There is an electric field and a gravitational field associated with the proton. Which of the following statements about the fields is not correct? A Field strength is a vector. B Potential is always less than 0. C Potential is proportional to 1 distance from proton D Field strength is proportional to 1 (distance from proton)2 (Total for Question 6 = 1 mark) 7 A pendulum of length l with a bob of mass m oscillates with frequency f. What is the frequency of a pendulum of length 4l with a bob of mass 2m? A 4 f B 2 f C f D f 2 (Total for Question 7 = 1 mark) 8 Which of the following lenses would produce a real image of an object placed 15 cm away from the lens? A converging, focal length = 10 cm B converging, focal length = 20 cm C diverging, focal length = 10 cm D diverging, focal length = 20 cm (Total for Question 8 = 1 mark)