A sensor is exposed for time t to a lamp of power P placed at a distance l. The sensor has an opening that is 4d in diameter. Assuming all energy of the lamp is given off as light, the number of photons entering the sensor if the wavelength of light is `lambda` is:

A sensor is exposed for 0.1 s to a 200 W lamp 10m away The sensor has an opening that is 20 mm in diameter. How many photons enter the sensor if the wavelength of light is 600nm? Assume that all the energy of the lamp is given off as light.

A sensor is exposed for 0.1 s to a 200 W lamp 10m away The sensor has an opening that is 20 mm in diameter. How many photons enter the sensor if the wavelength of light is 600nm? Assume that all the energy of the lamp is given off as light.

A photodiode sensor is used to measure the output of a 300 W lamp kept 10 m away. The sensor has an opening of 2 cm in diameter. How many photons enter the sensor if the wavelength of the light is 660 nm and the exposure time is 100 ms. (Assume that all the energy of the lamp is given off as light and h = 6.6 xx 10^(-34) Js )

In a photo electric effects set-up, a point source of light of poewer 3.2xx10^(-3) W emits mono energetic photons of energy 5.0 Ev. The source is located at a distance of 0.8m from the centre of a stationary metallic sphere of work function 3.0 Ev & of radius 8.0xx10^(6) m. The efficiency of photo electric emission is one of every 10^(6) incident photons. Assume that the sphere is isolated and initially neutral, and that photo electrons are instantly swept awy after emission. (a) Calculate the number of photo electrons emitted.per second. (b) Find the ratio of the wavelength of incident light to the de-Broglie wave length of the fastest photo electrons emitted. ltbr. (c) It is observed that the photo electron emission stops ata certain time tafter the light source is switched on. Why ? (d) Evaluate the time t.

A 200 W sodium street lamp emits yellow light of wavelength 0.6 μm. Assuming it to be 25% efficient in converting electrical energy to light, the number of photons of yellow light it emits per second is

A modern 200 W sodium street lamp emits yellow light of wavelength 0.6 mum . Assuming it to be 25% efficient in converting electrical energy to light, the number of photons of tellow light it emits per second is

A modern 200 W sodium street lamp emits yellow light of wavelength 0.6 mum . Assuming it to be 25% efficient in converting electrical energy to light, the number of photons of yellow light it emits per second is

A modern 200 W sodium street lamp emits yellow light of wavelength 0.6 mum . Assuming it to be 25% efficient in converting electrical energy to light, the number of photons of yellow light it emits per second is

A modern 200 W sodium street lamp emits yellow light of wavelength 0.6 mum . Assuming it to be 25% efficient in converting electrical energy to light, the number of photons of yellow light it emits per second is