Physics Past Questions and Answers

(a) Define ionization potential.<br/>(b)(i) State the three types of emission spectra.<br/>(ii) Name one source each which produces each of the spectra stated in (b)(i).<br/>(c) In an x-ray tube, electrons are accelerated the target by a potential difference of 80 A Calculate the:<br/>(i) speed of the electron;<br/>ii) threshold wavelength of the electron. [h=6.6 x 10\(^{-34}\) Js; e = 1.6 x 10\(^{-19}\) C; Me = 9.1 x 10\(^{-31}\)<br/>d) An x-ray photon of frequency 4.5 x 10\(^{-18}\) strikes an. electron, assumed to be at rest. If t electron absorbs all the photon energy, calculate the speed acquired by the electron. [ h = 6.6 x 10\(^{-34}\) Js; Me = 9.1 x 10\(^{-31}\) kg ]<br/> <br/>

(a) Define boiling point of a liquid.<br/>(b) Describe how water in a round bottom flask could be made to boil without heating it. [diagram not necessary]<br/>(c) State three applications of expansion of metals.<br/>(d) A room with floor measurements 7m x 10 m contains air of mass 250 kg at a temperature of 34°C. The air is cooled until the temperature falls to 24°C. Calculate the: (i) height of the room;<br/>(ii) quantity of energy extracted to cool the room;<br/>(iii) which is higher: the calculated value or the actual energy needed to cool the room? Give a reason for your answer. [ Specific heat capacity of air = 1010 Jkg\(^{-1}\)K\(^{-1}\); density of air = 1.25 kg m\(^{-3}]

A ball falling through a viscous liquid is acted upon by

A ball falling through a viscous liquid is acted upon by

An object of mass m moves with a uniform speed v round a circular path of radius r. If its angular speed is \(\omega\), the magnitude of the centripetal force acting on it is