I need help with these please

One day, after pulling down your window shade, you notice that sunlight is passing through a pinhole in the shade and making a small patch of light on the far wall. you see that the patch of light seems to be a circular diffraction pattern. it appears that the central maximum is about 1 cm across and you estimate that the distance from the window shade to the wall is about 3 m. what is (a) the average wavelength of sunlight? (b) the diameter of the pinhole?

An isotope undergoes radioactive decay by emitting radiation that has a –1 charge. what other characteristic does the radiation have?

Acapacitor is storing energy of 3 joules with a voltage of 50 volts across its terminals. a second identical capacitor of the same value is storing energy of 1 joule. what is the voltage across the terminals of the second capacitor?