QUESTION 1 A person with myopic vision normally wears contact lenses with a refractive power of 4129. They decide to order new eyeglasses that will sit 18 mm away from their eyes. What is the focal length of the lenses that they will need? Provide your answer in metres, to three decimal places, using the appropriate sign convention for lenses. 3.43 QUESTION 2 A van der Graa' generator is steadily charged up by a current of1 mA over a period of 0.2 s. Separately, a 43 g styrofoam ball is rubbed on a nylon sheet, transferring 'l .3 pl: ofcharge to the ball. It is then released 3 m away from the van der Graaff generator and is immediately repelled away. Ignoring gravity and air resistance, what is the magnitude ofthe acceleration experienced by the ball? Express your answer in mks units, correct to 2 decimal places. 6.04