#### Thank you for registering.

One of our academic counsellors will contact you within 1 working day.

Click to Chat

1800-1023-196

+91 7353221155

CART 0

• 0
MY CART (5)

Use Coupon: CART20 and get 20% off on all online Study Material

ITEM
DETAILS
MRP
DISCOUNT
FINAL PRICE
Total Price: Rs.

There are no items in this cart.
Continue Shopping

# infrared lamps are used in restaurants to keep the food warm. the infrared radiation is strongly absorbed by water, raising its temperature and that of the food. if the wavelength of the infrared radiation is assumed to be 1500nm, then the number of photons per second of infrared radiation produced by an infrared lamp that consumes energy at the rate of 100W and is 12% efficient only is y*10^(19). find the value of y.

Arun
25763 Points
2 years ago
use this equation to calculate energy per photon
E = hc/L

where..
E = energy per photon
h = planks constant = 6.626x10^-34 J x sec
c = speed of light = 3.00x10^8 m/s
L = wavelength = 1500nm = 1500nm x (1m / 10^9 nm) = 1.500x10^-6m

so that
E / photon = (6.626x10^-34 J x sec) x (3.00 m / sec) / (1.500x10^-6m) = 1.325x10^-19 J / photon

*******
then... since 1 W = 1 J / sec... we just convert to photons per sec using that E/photon.. like this

(1 photon / 1.325x10^-19J) x ((1 J / sec) / 1 W) x (0.12 x 100W) = 9.03x10^50 photons / sec

Hence y = 9 (approx)