A student determines the focal length of a device ‘x’ by focusing the image of a distant object on a screen placed 20cm from the device on the same side as the object. The device ‘X’ is

Two point charges are separated by a certain distance. how does the strength of the electric field produced by the first charge, at the position of the second charge, change if the second charge is doubled? a. the field does not change b. the field strength decreases by half. c. the field strength doubles d. the field strength quadruples

What you see with your eyes is a form of energy. a. light b. heat c. chemical d. electrical

Which of the following is a true statement about the acceleration ~a of the pendulum bob ~a is equal to the acceleration due to gravity. ~a is perpendicular to the bob’s trajectory. ~a is equal to the instantaneous rate of change in velocity. ~a is tangent to the bob’s trajectory.