An observer is using an astronomical refracting telescope to observe planets in normal adjustment. The focal lengths of the objective and eyepiece used in the telescope construction are \(20\text{m}\) and \(2\text{cm}\) respectively. Consider the following statements about the telescope:
(A)
the distance between the objective and the eyepiece is \(20.02\text{m}.\)
(B)
the magnification of the telescope is \(-1000\).
(C)
the image of the planet is erect and diminished.
(D)
the aperture of the eyepiece is smaller than that of the objective.
The correct statements are:
1.
A, B, and C
2.
B, C, and D
3.
C, D, and A
4.
A, B, and D
Subtopic: Telescope |
68%
Level 2: 60%+
NEET - 2022
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At any instant, two elements X1 and X2 have the same number of radioactive atoms. If the decay constant of X1 and X2 are 10 \(\lambda\) and \(\lambda\) respectively, then the time when the ratio of their atoms becomes \(\frac1e\) will be:
1. \(\frac{1}{11\lambda}\)
2. \(\frac{1}{9\lambda}\)
3. \(\frac{1}{6\lambda}\)
4. \(\frac{1}{5\lambda}\)
1. \(\frac{1}{11\lambda}\)
2. \(\frac{1}{9\lambda}\)
3. \(\frac{1}{6\lambda}\)
4. \(\frac{1}{5\lambda}\)
71%
Level 2: 60%+
NEET - 2022
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Six charges \(+q,\) \(-q,\) \(+q,\) \(-q,\) \(+q\) and \(-q\) are fixed at the corners of a hexagon of side \(d\) as shown in the figure. The work done in bringing a charge \(q_0\) to the centre of the hexagon from infinity is: (\(\varepsilon_0\text-\)permittivity of free space)
| 1. | zero | 2. | \(\dfrac{-q^2}{4\pi\varepsilon_0d}\) |
| 3. | \(\dfrac{-q^2}{4\pi\varepsilon_0d}\Big(3-\dfrac{1}{\sqrt2}\Big)\) | 4. | \(\dfrac{-q^2}{4\pi\varepsilon_0d}\Big(6-\dfrac{1}{\sqrt2}\Big)\) |
Subtopic: Electric Potential Energy |
84%
Level 1: 80%+
NEET - 2022
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An organ pipe filled with a gas at \(27^\circ \text{C}\) resonates at \(400~\text{Hz}\) in its fundamental mode. If it is filled with the same gas at \(90^\circ \text{C},\) the resonance frequency at the same mode will be:
| 1. | \(420~\text{Hz}\) | 2. | \(440~\text{Hz}\) |
| 3. | \(484~\text{Hz}\) | 4. | \(512~\text{Hz}\) |
Subtopic: Standing Waves |
70%
Level 2: 60%+
NEET - 2022
Hints
Subtopic: Graphs |
81%
Level 1: 80%+
NEET - 2022
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The collector current in a common base amplifier using n-p-n transistor is \(24\) mA. If \(80\text{%}\) of the electrons released by the emitter are accepted by the collector, then the base current is numerically:
1. \(6\) mA and leaving the base.
2. \(3\) mA and leaving the base.
3. \(6\) mA and entering the base.
4. \(3\) mA and entering the base.
1. \(6\) mA and leaving the base.
2. \(3\) mA and leaving the base.
3. \(6\) mA and entering the base.
4. \(3\) mA and entering the base.
Level 3: 35%-60%
NEET - 2022
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Three vessels of equal capacity have gases at the same temperature and pressure. The first vessel contains helium (monoatomic), the second contains fluorine (diatomic) and the third contains sulfur hexafluoride (polyatomic). The correct statement, among the following, is:
| 1. | All vessels contain an unequal number of respective molecules. |
| 2. | The root mean square speed of molecules is the same in all three cases. |
| 3. | The root mean square speed of helium is the largest. |
| 4. | The root mean square speed of sulfur hexafluoride is the largest. |
Subtopic: Types of Velocities |
75%
Level 2: 60%+
NEET - 2022
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In a gravitational field, the gravitational potential is given by; \(V=-\frac{K}{x}~\text{J/kg}.\) The gravitational field intensity at the point \((2,0,3)~\text m\) is:
| 1. | \(+\dfrac K2\) | 2. | \(-\dfrac{K}{2}\) |
| 3. | \(-\dfrac{K}{4}\) | 4. | \(+\dfrac K4\) |
Subtopic: Gravitational Field |
Level 3: 35%-60%
NEET - 2022
Hints
Two very long, straight, parallel conductor \(\mathrm{A}\) and \(\mathrm{B}\) carry current of \(5~\text{A}\) and \(10~\text{A}\) respectively and are at a distance of \(10~\mathrm{cm}\) from each other. The direction of the current in the two conductors is the same. The force acting per unit length between two conductors is:
(\(\mu_0=4\pi \times 10^{-7}\) SI unit)
(\(\mu_0=4\pi \times 10^{-7}\) SI unit)
| 1. | \(2\times10^{-4}~\text{Nm}^{-1}\) and is attractive |
| 2. | \(2\times10^{-4}~\text{Nm}^{-1}\) and is repulsive |
| 3. | \(1\times10^{-4}~\text{Nm}^{-1}\) and is attractive |
| 4. | \(1\times10^{-4}~\text{Nm}^{-1}\) and is repulsive |
Subtopic: Force between Current Carrying Wires |
75%
Level 2: 60%+
NEET - 2022
Hints
The magnetic field on the axis of a circular loop of radius \(100~\text{cm}\) carrying current \(I=\sqrt{2}~\text{A},\) at a point \(1~\text{m}\) away from the centre of the loop is given by:
| 1. | \(3.14 \times 10^{-7} ~\text{T} \) | 2. | \(6.28 \times 10^{-7} ~\text{T} \) |
| 3. | \(3.14 \times 10^{-4} ~\text{T} \) | 4. | \(6.28 \times 10^{-4} ~\text{T}\) |
Subtopic: Magnetic Field due to various cases |
58%
Level 3: 35%-60%
NEET - 2022
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