What happens to the intensity of light from a bulb if the distance from the bulb is doubled? As a laser beam travels across the length of a room, its intensity essentially remains constant. What geometrical characteristic of $LASER$ beam is responsible for the constant intensity which is missing in the case of light from the bulb ?
What happens to the intensity of light from a bulb if the distance from the bulb is doubled? As a laser beam travels across the length of a room, its intensity essentially remains constant. What geometrical characteristic of $LASER$ beam is responsible for the constant intensity which is missing in the case of light from the bulb ?
Intensity of waves is inversely proportional to source of distance from source $\left(\because\right.$ I $\left.\propto \frac{1}{r^{2}}\right)$ when distance become double then intensity become $\frac{1}{4}^{\text {th }}$ value they do not spread hence here inten sity remains same.
Following geometric characteristics of LASER beam are responsible for constant intensity,
$(i)$ Unidirectional
$(ii)$ Monochromatic
$(iii)$ Coherent light
$(iv)$ Highly collimated
These characteristics are absent in case of bulb in given case.
Similar Questions
The electric field of a plane electromagnetic wave varies with time of amplitude $2\, Vm^{-1}$ propagating along $z$ -axis. The average energy density of the magnetic field (in $J\, m^{-3}$) is
The electric field of a plane electromagnetic wave varies with time of amplitude $2\, Vm^{-1}$ propagating along $z$ -axis. The average energy density of the magnetic field (in $J\, m^{-3}$) is
Light wave is travelling along $y-$ direction. If the corresponding $\vec E$ vector at any time is along the $x-$ axis, the direction of $\vec B$ vector at that time is along
Light wave is travelling along $y-$ direction. If the corresponding $\vec E$ vector at any time is along the $x-$ axis, the direction of $\vec B$ vector at that time is along
A point source of electromagnetic radiation has an average power output of $800\,W$ . The maximum value of electric field at a distance $3.5\,m$ from the source will be.....$V/m$
A point source of electromagnetic radiation has an average power output of $800\,W$ . The maximum value of electric field at a distance $3.5\,m$ from the source will be.....$V/m$
Aplane electromagnetic wave is incident on a plane surface of area A normally, and is perfectly reflected. If energy $E$ strikes the surface in time $t$ then average pressure exerted on the surface is ( $c=$ speed of light)
Aplane electromagnetic wave is incident on a plane surface of area A normally, and is perfectly reflected. If energy $E$ strikes the surface in time $t$ then average pressure exerted on the surface is ( $c=$ speed of light)
The magnetic field in a plane electromagnetic wave is given by
${B_y} = \left( {2 \times {{10}^{ - 7}}} \right)\sin \left( {0.5 \times {{10}^3}x + 1.5 \times {{10}^{11}}t} \right)T$
$(a)$ What is the wavelength and frequency of the wave?
$(b)$ Write an expression for the electric field.
The magnetic field in a plane electromagnetic wave is given by
${B_y} = \left( {2 \times {{10}^{ - 7}}} \right)\sin \left( {0.5 \times {{10}^3}x + 1.5 \times {{10}^{11}}t} \right)T$
$(a)$ What is the wavelength and frequency of the wave?
$(b)$ Write an expression for the electric field.