Five lumen/watt is the luminous efficiency of | vedclass

Name: Exam Paper Generator | JEE NEET Paper Generator | Vedclass
Brand: Vedclass
Rating: 5 (35 reviews)

Question

(C) The luminous efficiency $\eta$ is defined as the ratio of luminous flux $\phi$ to the power $P$ consumed by the lamp: $\eta = \frac{\phi}{P} \impl

Vedclass · Accepted Answer

$88$

Vedclass · Answer

(C) The luminous efficiency $\eta$ is defined as the ratio of luminous flux $\phi$ to the power $P$ consumed by the lamp: $\eta = \frac{\phi}{P} \implies \phi = \eta 	imes P$. The luminous intensity $L$ is related to the total luminous flux $\phi$ emitted by a point source in all directions by the formula: $L = \frac{\phi}{4\pi} \implies \phi = 4\pi L$. Equating the two expressions for $\phi$: $\eta 	imes P = 4\pi L$. Solving for power $P$: $P = \frac{4\pi L}{\eta}$. Given $\eta = 5 	ext{ lumen/watt}$ and $L = 35 	ext{ candela}$,we substitute these values: $P = \frac{4 	imes 3.14159 	imes 35}{5} = 4 	imes 3.14159 	imes 7 = 28 	imes 3.14159 \approx 87.96 \, W$. Rounding to the nearest whole number,we get $P \approx 88 \, W$.

Five lumen/watt is the luminous efficiency of a lamp and its luminous intensity is $35$ candela. The power of the lamp is.......$W$

Similar Questions

Ray optics is valid when characteristic dimensions are:

$A$ good photographic print is obtained at a distance of $20 \,cm$ with an exposure time of $2 \,s$. What will be the exposure time required to get an equally good result at a distance of $40 \,cm$?

Assertion: By roughening the surface of a glass sheet,its transparency can be reduced.
Reason: Glass sheet with a rough surface absorbs more light.

$A$ prism having an apex angle $4^o$ and refractive index $1.5$ is located in front of a vertical plane mirror as shown in the figure. Through what total angle is the ray deviated after reflection from the mirror (in $^o$)?

What is rectilinear propagation of light? Explain ray of light and beam of light.

Vedclass Test Series

Exam Paper Generator

Online Exam Module