Question
$Lux$ is equal to

Answer

( c)$I = \frac{L}{{{r^2}}}$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Similar questions

The diode shown in the circuit is a silicon diode. The potential difference between the points $A$ and $B$ will be.....$V$
A uniform rod of mass $M$ and length $L$ is hinged about a point as shown in the fig. Initially the rod is kept horizontal by a massless string as shown. When string is cut the angular acceleration of the rod is 
The masses of blocks A and B are $m$ and $M$ respectively. Between $A$ and $B$, there is a constant frictional force $F$ and $B$ can slide on a smooth horizontal surface. A is set in motion with velocity while $B$ is at rest. What is the distance moved by A relative to $B$ before they move with the same velocity?
The carrier frequency generated by a tank circuit containing $1 \,nF$ capacitor and $10 \mu H$ inductor is
A coil is suspended in a uniform magnetic field, with the plane of the coil parallel to the magnetic lines of force. When a current is passed through the coil it starts oscillating; It is very difficult to stop. But if an aluminium plate is placed near to the coil, it stops. This is due to
The excess pressure in a soap bubble is thrice that in other one. Then the ratio of their volume is
A body starts to fall freely under gravity. The distances covered by it in first, second and third second are in ratio
Projectiles $A$ and $B$ are thrown at angles of $45^{\circ}$ and $60^{\circ}$ with vertical respectively from top of a $400 \mathrm{~m}$ high tower. If their ranges and times of flight are same, the ratio of their speeds of projection $v_A: v_B$ is :
A disc is rotating with angular velocity $\vec{\omega}$. A force $\vec{F}$ acts at a point whose position vector with respect to the axis of rotation is $\vec{r}$. The power associated with torque due to the force is given by ..........
In double slit experiment, the wavelength $\lambda $ of the light source $400\ nm$ , the slit seperation $d$ is $20\ \mu m$ and the individual slit width a is $4\ \mu m$ . Consider the interference of the light from the two slits and also the diffraction of light through each slit. Find number bright interference fringes are within the central peak of diffraction envelope