lamp 120 12° 0.7 m 5.0 m ground 1.A bicycle light bulb runs off a 6.0 volt battery, and draws a current of 0.50 ampere....
lamp 120 12° 0.7 m 5.0 m ground 1.A bicycle light bulb runs off a 6.0 volt battery, and draws a current of 0.50 ampere. 80% of the electrical power input is converted into radiant output, with a luminous efficacy of 16 lumen/watt. A reflector directs all the light from the bulb into a uniform cone of light, of half-angle 12°. The lamp is mounted on a bicycle at a height of 0.70 m above the ground, and the centre of the beam hits the ground at a point P which is 5.0 m in front, as shown in the diagram (i) What is the luminous power output of the lamp? (ii) What is the luminous intensity of the lamp? (iii) What is the illuminance produced on the ground surface at point P? [10]
lamp 120 12° 0.7 m 5.0 m ground 1.A bicycle light bulb runs off a 6.0 volt battery, and draws a current of 0.50 ampere. 80% of the electrical power input is converted into radiant output, with a luminous efficacy of 16 lumen/watt. A reflector directs all the light from the bulb into a uniform cone of light, of half-angle 12°. The lamp is mounted on a bicycle at a height of 0.70 m above the ground, and the centre of the beam hits the ground at a point P which is 5.0 m in front, as shown in the diagram (i) What is the luminous power output of the lamp? (ii) What is the luminous intensity of the lamp? (iii) What is the illuminance produced on the ground surface at point P? [10]