A spring is stretched by 5 cm by a force 10 N. The time period of the oscillations when a mass of 2 kg is suspended by it is:
(1) 0.0628 s
(2) 6.28 s
(3) 3.14 s
(4) 0.628 s Continue reading A spring is stretched by 5 cm by a force 10 N ….
Category Archives: Physics
An electromagnetic wave of wavelength $’\lambda ‘$ ….
An electromagnetic wave of wavelength $’\lambda ‘$ is incident on a photosensitive surface of negligible work function. If ‘m’ mass of photoelectron emitted from the surface has de-Broglie wavelength $\lambda_d$, then:
(1) $\lambda = \left( {\frac{{2m}}{{hc}}} \right){\lambda _d}^2$
(2) ${\lambda _d} = \left( {\frac{{2mc}}{h}} \right){\lambda ^2}$
(3) $\lambda = \left( {\frac{{2mc}}{h}} \right){\lambda _d}^2$
(4) $\lambda = \left( {\frac{{2h}}{{mc}}} \right){\lambda _d}^2$ Continue reading An electromagnetic wave of wavelength $’\lambda ‘$ ….
A cup of coffee cools from $90^{\circ}$C ….
A cup of coffee cools from $90^{\circ}$C to $80^{\circ}$C in t minutes when the room temperature is $20^{\circ}$C. The time taken by a similar cup of coffee to cool from $80^{\circ}$C to $60^{\circ}$C at the same room temperature $20^{\circ}$C is:
(1) $\frac {13}{10}$t
(2) $\frac {13}{5}$t
(3) $\frac {10}{13}$t
(4) $\frac {5}{13}$t Continue reading A cup of coffee cools from $90^{\circ}$C ….
The number of photons per second on an average ….
The number of photons per second on an average emitted by the source of monochromatic light of wavelength 600 nm, when it delivers the power of $3.3 \times 10^{-3}$ watt will be: ($h=6.6\times 10^{-34}$Js)
(1) $10^{18}$
(2) $10^{17}$
(3) $10^{16}$
(4) $10^{15}$ Continue reading The number of photons per second on an average ….
A particle moving in a circle of radius R ….
A particle moving in a circle of radius R with a uniform speed takes time T to complete one revolution. If this particle were projected with the same speed at an angle ‘$\theta $’ to the horizontal, the maximum height attained by it equals 4R. The angle of projection ‘$\theta $’ is then given by:
(1) $\theta = {\cos ^{ – 1}}\sqrt {\frac{{g{T^2}}}{{{\pi ^2}R}}} $
(2) $\theta = {\cos ^{ – 1}}\sqrt {\frac{{{\pi ^2}R}}{{g{T^2}}}} $
(3) $\theta = {\sin ^{ – 1}}\sqrt {\frac{{{\pi ^2}R}}{{g{T^2}}}} $
(4) $\theta = {\sin ^{ – 1}}\sqrt {\frac{{2g{T^2}}}{{{\pi ^2}R}}} $ Continue reading A particle moving in a circle of radius R ….
$R=\frac {V}{I}$$V=(50\pm 2) V$$I=(20 \pm 0.2 ) A $% Error = ?
The resistance $R=\frac {V}{I}$, where $V=(50\pm 2) V$ and $I=(20 \pm 0.2 ) A $. The percentage error in R is ‘x’ %. The value of ‘x’ to the nearest integer is _ _ _ _ . Continue reading $R=\frac {V}{I}$
$V=(50\pm 2) V$
$I=(20 \pm 0.2 ) A $
% Error = ?
Hand Washing ~ Q & A
Q: After meals you wash your hands and due to non-availability of towel you shake your hands to remove the water as much as possible. What makes water remove in this process? Continue reading Hand Washing ~ Q & A