Your friend has set up a converging lens with a focal length of 22 cm. On one side of the lens, 22 cm from its center, she has an object. She is holding a white card on the
opposite side of the lens, but she can't get an image to form. What might be the
problem?

She is using a card instead of paper.
She has the card on the wrong side of the lens.
She has set the object at the secondary focus, a position where the lens will not
form an image.
She has set the object at the primary focus, a position where the lens will not
form an image.