English
Karnataka Board PUCPUC Science Class 11

As the Wavelength is Increased from Violet to Red, the Luminosity - Physics

Advertisements
Advertisements

Question

As the wavelength is increased from violet to red, the luminosity ____________ .

Options

  • continuously increases

  • continuously decreases

  • increases then decreases

  • decreases then increases

MCQ
Fill in the Blanks
Advertisements

Solution

increases then decreases

 

The luminosity first increases up to 555 nm and then decreases.

shaalaa.com
Light Process and Photometry
  Is there an error in this question or solution?
Chapter 22: Photometry - MCQ [Page 454]

APPEARS IN

HC Verma Concepts of Physics Vol. 1 [English] Class 11 and 12
Chapter 22 Photometry
MCQ | Q 3 | Page 454

RELATED QUESTIONS

Light is incident normally on a small plane surface. If the surface is rotated by an angle of 30° about the incident light, does the illuminance of the surface increase, decreases or remain same? Does your answer change if the light did not fall normally on the surface?


The one parameter that determines the brightness of a light source sensed by an eye is ____________ .


Three light sources A, B and C emit equal amount of radiant energy per unit time. The wavelengths emitted by the three source are 450 nm, 555 nm and 700 nm respectively. The brightness sensed by an eye for the sources are XA, XB and XC respectively. Then, ________ .


An electric bulb is hanging over a table at a height of 1 m above it. The illuminance on the table directly below the bulb is 40 lux. The illuminance at a point on the table 1 m away from the first point will be about ___________ .


A photographic plate placed a distance of 5 cm from a weak point source is exposed for 3 s. If the plate is kept at a distance of 10 cm from the source, the time needed for the same exposure is _____________ .


Figure shows a glowing mercury tube. The intensities at point A, B and C are related as __________ .


A room is illuminated by an extended source. The illuminance at a particular portion of a wall can be increased by

(a) moving the source

(b) rotating the source

(c) bringing some mirrors in proper positions

(d) changing the colour of the source.


A source emits 45 joules of energy in 15 s. What is the radiant flux of the source?


The luminous flux of a monochromatic source of 1 W is 450 lumen watt−1. Find the relative luminosity at the wavelength emitted.


A light source emits monochromatic light of  555 nwavelengthm. The source consumes 100 W of electric power and emits 35 W of radiant flux. Calculate the overall luminous efficiency.


A source emits 31.4 W of radiant flux distributed uniformly in all directions. The luminous efficiency is 60 lumen watt−1. What is the luminous intensity of the source?


The illuminance of  a small area changes from 900 lumen m−2 to 400 lumen m−2 when it is shifted along its normal by 10 cm. Assuming that it is illuminated by a point source placed on the normal, find the distance between the source and the area in the original position.


Figure shows a small diffused plane source S placed over a horizontal table-top at a distance of 2.4 m with its plane parallel to the table-top. The illuminance at the point Adirectly below the source is 25 lux. Find the illuminance at a point B of the table at a distance of 1.8 m from A.


An electric lamp and a candle produce equal illuminance at a photometer screen when they are placed at 80 cm and 20 cm from the screen respectively. The lamp is now covered with a thin paper which transmits 49% of the luminous flux. By what distance should the lamp be moved to balance the intensities at the screen again?


Two light sources of intensities 8 cd and 12 cd are placed on the same side of a photometer screen at a distance of 40 cm from it. Where should a 80 cd source be placed to balance the illuminance?


Share
Notifications

Englishहिंदीमराठी


      Forgot password?
Use app×