Arating plate for an electric toaster states: 230 volts, 50hz, 800 watts. state the frequency of the mains supple and give the power rating of the toaster.

Which pair of quantities includes one quantity that increases as the other decreases during simple harmonic motion?

Aphoton is absorbed by an electron that is in the n = 3 state of a hydrogen atom, causing the hydrogen atom to become ionized. very far away from the nucleus, the released electron has a velocity of 750,000 m/s. what was the wavelength of the absorbed photon?

Aresistor with an unknown resistance is connected in parallel to a 9 ω resistor. when both resistors are connected in parallel to an emf source of 21 v, the current through the unknown resistor is measured with an ammeter to be 4 a. what is the resistance of the unknown resistor? answer in units of ω.