| 151 |
The fringe width in a double-slit experiment in air is 4 mm. What is it when the whole apparatus is placed in… |
Physics
Wave optics |
Medium |
| 152 |
Light of wavelength 500 nm falls on a single slit of width 0.2 mm. What is the width of the central maximum o… |
Physics
Wave optics |
Hard |
| 153 |
On a graph of stopping potential V₀ against frequency ν for a photocell, the slope of the straight line equal… |
Physics
Photoelectric effect |
Easy |
| 154 |
Light of frequency below the threshold frequency falls on a metal. What happens if its intensity is increased… |
Physics
Photoelectric effect |
Easy |
| 155 |
In a photoelectric experiment the frequency is kept fixed above threshold and the intensity is doubled. What … |
Physics
Photoelectric effect |
Medium |
| 156 |
Light of wavelength 310 nm falls on a metal whose work function is 2.5 eV. What is the stopping potential, ap… |
Physics
Photoelectric effect |
Medium |
| 157 |
A metal has a work function of 2.0 eV. What is its threshold frequency, approximately? (h = 6.63 × 10⁻³⁴ J s,… |
Physics
Photoelectric effect |
Hard |
| 158 |
The de Broglie wavelength of a particle of momentum p is: |
Physics
Matter waves |
Easy |
| 159 |
If the momentum of an electron is doubled, its de Broglie wavelength becomes: |
Physics
Matter waves |
Easy |
| 160 |
What is the de Broglie wavelength of an electron accelerated from rest through 100 V? |
Physics
Matter waves |
Medium |
| 161 |
A cricket ball of mass 0.12 kg moves at 20 m/s. What is its de Broglie wavelength, approximately? (h = 6.63 ×… |
Physics
Matter waves |
Medium |
| 162 |
A proton and an alpha particle are each accelerated from rest through the same potential difference. What is … |
Physics
Matter waves |
Hard |
| 163 |
In the alpha-particle scattering experiment, most alpha particles passed straight through the gold foil. This… |
Physics
Atomic models |
Easy |
| 164 |
What is the energy of the electron in the n = 3 orbit of a hydrogen atom? |
Physics
Atomic models |
Easy |
| 165 |
The radius of the first Bohr orbit of hydrogen is 0.529 Å. What is the radius of the second orbit? |
Physics
Atomic models |
Medium |
| 166 |
An electron in a hydrogen atom jumps from n = 3 to n = 2. What are the photon energy and wavelength, approxim… |
Physics
Atomic models |
Medium |
| 167 |
What is the shortest wavelength in the Lyman series of hydrogen? (R = 1.097 × 10⁷ m⁻¹) |
Physics
Atomic models |
Hard |
| 168 |
How many neutrons are present in a nucleus of ²³⁸₉₂U? |
Physics
Nucleus |
Easy |
| 169 |
Which property correctly describes the nuclear force between nucleons? |
Physics
Nucleus |
Easy |
| 170 |
¹⁹⁸₈₀Hg and ¹⁹⁷₇₉Au are examples of: |
Physics
Nucleus |
Medium |
| 171 |
Taking R₀ = 1.2 fm, what is the radius of the ²⁷Al nucleus? |
Physics
Nucleus |
Medium |
| 172 |
What is the ratio of the radius of a nucleus with mass number 125 to that of a nucleus with mass number 8? |
Physics
Nucleus |
Hard |
| 173 |
The energy equivalent of 1 atomic mass unit is about: |
Physics
Mass-energy and binding energy |
Easy |
| 174 |
The binding energy per nucleon is highest for nuclei with mass number close to: |
Physics
Mass-energy and binding energy |
Easy |
| 175 |
If 1 g of matter were completely converted into energy, how much energy would be released? |
Physics
Mass-energy and binding energy |
Medium |
| 176 |
Given m(¹H) = 1.007825 u, m_n = 1.008665 u and m(²H) = 2.014102 u, what is the binding energy of the deuteron? |
Physics
Mass-energy and binding energy |
Medium |
| 177 |
Using m(¹H) = 1.007825 u, m_n = 1.008665 u and m(⁴He) = 4.002603 u, what is the binding energy per nucleon of… |
Physics
Mass-energy and binding energy |
Hard |
| 178 |
In a nuclear reactor, cadmium rods are used to: |
Physics
Nuclear fission and fusion |
Easy |
| 179 |
The main purpose of a moderator such as heavy water in a reactor is to: |
Physics
Nuclear fission and fusion |
Easy |
| 180 |
In the reaction ²³⁵₉₂U + ¹₀n → ¹⁴⁴₅₆Ba + ⁸⁹₃₆Kr + x ¹₀n, what is the value of x? |
Physics
Nuclear fission and fusion |
Medium |
| 181 |
Nuclear fusion needs extremely high temperatures mainly because: |
Physics
Nuclear fission and fusion |
Medium |
| 182 |
Each fission of U-235 releases about 200 MeV. Roughly how much energy is released if all the nuclei in 1 kg o… |
Physics
Nuclear fission and fusion |
Hard |
| 183 |
In which type of solid do the valence and conduction bands overlap? |
Physics
Energy bands |
Easy |
| 184 |
Diamond is a good electrical insulator mainly because: |
Physics
Energy bands |
Easy |
| 185 |
A pure silicon crystal is cooled to 0 K. How does it behave? |
Physics
Energy bands |
Medium |
| 186 |
As the temperature of a pure semiconductor increases, its resistance: |
Physics
Energy bands |
Medium |
| 187 |
Silicon has a band gap of 1.1 eV. What is the longest wavelength of light that can excite an electron from it… |
Physics
Energy bands |
Hard |
| 188 |
To make n-type silicon, the impurity added should be: |
Physics
Semiconductors |
Easy |
| 189 |
In a p-type semiconductor, the majority charge carriers are: |
Physics
Semiconductors |
Easy |
| 190 |
An n-type semiconductor has many more free electrons than holes. What is the net charge on the crystal? |
Physics
Semiconductors |
Medium |
| 191 |
In the energy band diagram of a p-type semiconductor, the acceptor energy level lies: |
Physics
Semiconductors |
Medium |
| 192 |
Silicon with nᵢ = 1.5 × 10¹⁶ m⁻³ is doped so that the electron concentration is 5 × 10²² m⁻³. What is the hol… |
Physics
Semiconductors |
Hard |
| 193 |
When a p-n junction is forward biased, the width of the depletion region: |
Physics
p-n junction diode |
Easy |
| 194 |
The small current through a reverse-biased p-n junction is mainly due to: |
Physics
p-n junction diode |
Medium |
| 195 |
A full-wave rectifier is fed from 50 Hz AC mains. What is the fundamental frequency of the ripple in its outp… |
Physics
p-n junction diode |
Medium |
| 196 |
In the forward-bias region of a diode, increasing the voltage by 0.1 V increases the current by 20 mA. What i… |
Physics
p-n junction diode |
Easy |
| 197 |
A silicon diode with a forward voltage drop of 0.7 V is connected in forward bias in series with a 1 kΩ resis… |
Physics
p-n junction diode |
Hard |