A 100 watt lamp is rated at 0.8 watt per andela. What is the luminous flux of the source and illuminance produced by it at a distance of 2 metres?

A short bar magnet has a magnetic moment of 0.2 JT(-1) . Calculate the magnitude of the magnetic field produced by the magnet at a distance of 8 cm from the centre of the magnet on the equitorial line of the magnet.

A short bar magnet has a magnetic moment of 0.2 JT^(-1) . Calculate the magnitude of the magnetic field produced by the magnet at a distance of 8 cm from the centre of the magnet on the equitorial line of the magnet.

Two lamps A rated 100 watt 220 V and B rated 60 watt 220 V are connected in series to electric main supply of 220 V. the ratio of heat produced in lamp A to the lamp B would be

Two long straight parallel conductors 'a' and 'b', carrying steady currents Ia and Ib are separated by a distance d. Write the magnitude and direction of the magnetic field produced by the conductor 'a' at the points along the conductor 'b'.If the currents are flowing in the same direction, what is the nature and magnitude of the force between the two conductors ? F_(BA) = (mu_0I_A I_B L)/(2pid)

A 100 W (Watt) sodium Lamp radiated energy uniformly in all directions. The lamp is located at the centre of a large sphere, that absorbs all the sodium light which is incident on it. The wavelength of the sodium light is 589 nm(nano metre): At what rate are the photons delivered to the sphere?

A 60 volt , 10 watt lamp is to be run on 100 volt-60 hertz a.c. mains. Calculate if resistance is to be used instead of choke, what wil be its value?

Suppose we represent the distance above the ground by a positive integer and that below the ground by a negative integer, then answer the following: An elevator descends into a mine shaft at the rate of 5 metre per minute. What will be its positin after one hour?

In a photoelectric effect set up, a point source of light of power 3.2 xx10^(-3) W emits monoenergetic photons of energy 5eV.The source is located at a distance of a stationary metallic sphere of work function 3eV and radius 8xx10^(-3)m .The efficiency of photoelectron emission is one for every 10^(6) incident photons.Assume that the sphere is isolated and initially neutral and the photoelectrons are initially swept away after emission. Calculate the number of photoelectrons emitted per second.

A telescope has an objective of diameter of 60 cm. The focal lengths of the objective and eye piece are 2.0 m and 1.0 cm respectively. The telescope is directed to view two distant almost point sources of light (e.g. two stars of a binary). The sources are at roughly the same distance (=10^4 light years) along the line of sight but separated transverse to the line of sight by a distnace of 10^10 m . what will the telescope resolve the two objects i.e. will it see two distinct stars?