The wave function of a metal is 8.0 x \(10^{-19}\)J. Calculate the wavelength of its threshold frequency. (Speed of light in a vacuum = 3 x \(10^8ms^{-1}, Planck's constant = 6.6 \times 10^{-34}\)Js)
A cell of e.m.f. 1.5V and internal resistance of 2.5Ω is connected in series with an ammeter of resistance 0.5W and a resistor of resistance of 7.0Ω. Calculate the current in the circuit.
A ball is dropped from a height of 45m above the ground. Calculate the velocity of the ball just before it strikes the ground. (Neglect air resistance and take g as \(10ms^{-2}\)
