A lens 17.8 cm from an object
forms an image 52.5 cm from the
lens. What is the focal length of
the lens?
Unit=cm

focal length = 13.33 cm

Explanation:

1/f = 1/p + 1/q

= 1/17.8 + 1/52.5

= 0.056 + 0.019

1/f = 0.075

do

f=1/0.075

f= 13.33 cm

c) up is the direction the magnetic force is acting on the charge.

the answer is the first electromagnet (a). this is because it has more coils around the ferromagnetic material. increasing the number of coils increases the surface area in which the metal interacts with the current in the coil. this enables more atoms in the metal to become aligned hence becoming more magnetized.