MCQ
How many types of electron emissions exist?
- A$2$
- B$3$
- ✓$4$
- D$1$
✓
Answer
Correct option: C.
$4$
There are four types of electron emissions, namely, thermionic emission, photoelectric emission, secondary emission, and field emission. These are the different methods of producing electron emissions.
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
In an experiment with a convex lens. The plot of the image distance ($v'$) against the object distance $\left(\mu^{\prime}\right)$ measured from the focus gives a curve $v^{\prime} \mu^{\prime}=225$. If all the distances are measured in $cm$. The magnitude of the focal length of the lens is $cm$.
→A parallel plate capacitor is formed by two plates each of area $30 \pi\, cm ^{2}$ separated by $1\, mm$. A material of dielectric strength $3.6 \times 10^{7} \,Vm ^{-1}$ is filled between the plates. If the maximum charge that can be stored on the capacitor without causing any dielectric breakdown is $7 \times 10^{-6}\, C$, the value of dielectric constant of the material is
→$\left\{ Use : \frac{1}{4 \pi \varepsilon_{0}}=9 \times 10^{9} Nm ^{2} C ^{-2}\right\}$
A parallel - plate capacitor with plate area $A$ has separation $d$ between the plates. Two dielectric slabs of dielectric constant ${K}_{1}$ and ${K}_{2}$ of same area $\frac A2$ and thickness $\frac d2$ are inserted in the space between the plates. The capacitance of the capacitor will be given by :
→Assertion : Neutrons penetrate mater more readily as compared to protons.
Reason : Neutrons are slightly more massive than protons.
A denser medium of refractive index $1.5$ has a concave surface of radius of curvature $12\,cm$. An object is situated in the denser medium at a distance of $9 \,cm$ from the pole. Locate the image due to refraction in air.
→Work function of a metal is $2.1 eV$. Which of the waves of the following wavelengths will be able to emit photoelectrons from its surface
→The thinnest bubble film in air that can possibly strongly reflect red light because of constructive interference makes up a certain bubble. How could we create the thinnest bubble film that will strongly reflect purple light?
If the turns ratio of a transformer is $2$ and the impedance of primary coil is $250 \ W$ then the impedance of secondary coil will be.
→What causes chromatic aberration?
Half life period of a radioactive sample is $T$. Let $x$ fraction disintegrates in time $'t'$. How much fraction will decay in $'\frac{t}{2}'$ time
→