MCQ
Identify the incorrect relationship
  • A
    Number of waves in an orbit, $n=\frac{2 \pi r}{\lambda}$
  • B
    Number of revolutions of an electron per second in $n^{ m }$ orbit $=\frac{v_n}{2 \pi r_n}$
  • C
    Wavelength of an electron $=\frac{h}{p}$
  • Speed of a (de-Broglie wavelength) particle accelerated by a potential difference $V$ is $v=\frac{2 e V}{m}$

Answer

Correct option: D.
Speed of a (de-Broglie wavelength) particle accelerated by a potential difference $V$ is $v=\frac{2 e V}{m}$
d
(d)

Kinetic energy gained by an electron accelerated by potential $V$ is

$K E=e V$

or $\frac{1}{2} m v^2=e V$

$v=\sqrt{\frac{2 e V}{m}}$

Hence $(d)$ is wrong.

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

Six charges, three positive and three negative of equal magnitude are to be placed at the vertices of a regular hexagon such that the electric field at $O$ is double the electric field when only one positive charge of same magnitude is placed at $R$. Which of the following arrangements of charges is possible for $P,\,Q,\,R,\,S,\,T,\,$ and $U$ respectively
A compound of molecular formula $C_8H_8O_2$ reacts with acetophenone to form a single cross-aldol product in the presence of base. The same compound on reaction with conc. $NaOH$ forms benzyl alcohol as one of the products. The structure of the compound is
A ball is projected with kinetic energy $E$, at an angle of $60^{\circ}$ to the horizontal. The kinetic energy of this ball at the highest point of its flight will become.
$A$ thin rod of length $L$ is placed vertically on a frictionless horizontal floor and released with a negligible push to allow it to fall. At any moment, the rod makes an angle $\theta$ with the vertical. If the center of mass has acceleration $= A$, and the rod an angular acceleration $= \alpha$ at initial moment, then
The ratio of the radius of a planet $‘A’$ to that of planet $‘B’$ is $‘r’$. The ratio of acceleration due to gravity on the planets is $‘x’$. The ratio of the escape velocities from the two planets is
The product formed in Aldol condensation is
A circuit has a section $AB$ as shown in the figure. If the potential difference between  points $A$ and $B$ is $V\, volt$, then potential difference across $C_1$ is
An object, moving with a speed of $6.25\ m/s,$ is decelerated at a rate given by : $\frac{{dv}}{{dt}} = - 2.5\sqrt v $ where $v$ is the instantaneous speed. The time taken by the object, to come to rest, would be $........s$
The mass of the moon is about $1.2\%$ of the mass of the earth. Compared to the gravitational force the earth exerts on the moon, the gravitational force the moon exerts on earth
A point object of mass $m$ is kept at $(a, 0)$ along $x$-axis. What mass should be kept at $(-3 a, 0)$, so that centre of mass lies at origin?