MCQ
Focal length of a plane mirror is
  • A
    Zero
  • Infinite
  • C
    Very less
  • D
    Indefinite

Answer

Correct option: B.
Infinite
$f=\frac{R}{2}$, and $R=\infty$ for plane mirror.

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

A calorimeter of mass $0.2 \mathrm{~kg}$ and specific heat $900 \mathrm{~J} / \mathrm{kg}-\mathrm{K}$. Containing $0.5 \mathrm{~kg}$ of a liquid of specific heat $2400 \mathrm{~J} / \mathrm{kg}-\mathrm{K}$. Its temperature falls from $60^{\circ} \mathrm{C}$ to $55^{\circ} \mathrm{C}$ in one minute. The rate of cooling is
The magnifying power of a simple microscope is $6.$ The focal length of its lens in metres will be, if least distance of distinct vision is $25 \mathrm{~cm}$
A ray of light travels from an optically denser to rarer medium. The critical angle for the two media is $C$. The maximum possible deviation of the ray will be
The smallest temperature difference that can be measured with a combination of a thermocouple of thermo e.m.f. $30 \mu V$ per degree and a galvanometer of $50 ohm$ resistance, capable of measuring a minimum current of $3 \times 10 amp$ is
Two bars of thermal conductivities $K$ and $3 K$ and lengths $1 \mathrm{~cm}$ and $2 \mathrm{~cm}$ respectively have equal cross-sectional area, they are joined lengths wise as shown in the figure. If the temperature at the ends of this composite bar is $0^{\circ} \mathrm{C}$ and $100^{\circ} \mathrm{C}$ respectively (see figure), then the temperature $\phi$ of the interface isImage
An AM wave has $1800$ watt of total power content, For $100 \%$ modulation the carrier should have power content equal to
There are three voltmeters of the same range but of resistances $10000 \Omega, 8000 \Omega$ and $4000 \Omega$ respectively. The best voltmeter among these is the one whose resistance is
Progressive wave of sound is represented by $y=a \sin [400\  \pi t-\pi x / 6.85]$ where $x$ is in $m$ and $t$ is in sec. Frequency of the wave will be
The dimensions of couple are
An ideal monoatomic gas is taken round the cycle $A B C D A$ as shown in following $P-V$ diagram. The work done during the cycle is
Image