The half-life of a radioactive substance is \(20\) minutes. In how much time, the activity of substance drops to \((\frac{1}{16})^{\mathrm{th}}\) of its initial value?
1. \(80\) minutes
2. \(20\) minutes
3. \(40\) minutes
4. \(60\) minutes
Subtopic: Radioactivity (OLD NCERT) |
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The net magnetic flux through any closed surface is:
1. negative
2. zero
3. positive
4. infinity
1. negative
2. zero
3. positive
4. infinity
Subtopic: Analogy between Electrostatics & Magnetostatics |
84%
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A metal wire has mass \((0.4\pm 0.002)~\mathrm{g}\), radius \((0.3\pm 0.001)~\mathrm{mm}\) and length \((5\pm 0.02)~\mathrm{cm}\). The maximum possible percentage error in the measurement of density will nearly be:
1. \(1.4 \%\)
2. \(1.2 \%\)
3. \(1.3 \%\)
4. \(1.6 \%\)
1. \(1.4 \%\)
2. \(1.2 \%\)
3. \(1.3 \%\)
4. \(1.6 \%\)
Subtopic: Errors |
From NCERT
NEET - 2023
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The angular acceleration of a body, moving along the circumference of a circle, is:
| 1. | along the axis of rotation |
| 2. | along the radius, away from centre |
| 3. | along the radius towards the centre |
| 4. | along the tangent to its position |
Subtopic: Rotational Motion: Kinematics |
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The magnetic energy stored in an inductor of inductance \(4~\mathrm{\mu H}\) carrying a current of \(2~\text{A}\) is:
1. \(8~\mathrm{\mu J}\)
2. \(4~\mathrm{\mu J}\)
3. \(4~\mathrm{mJ}\)
4. \(8~\mathrm{mJ}\)
1. \(8~\mathrm{\mu J}\)
2. \(4~\mathrm{\mu J}\)
3. \(4~\mathrm{mJ}\)
4. \(8~\mathrm{mJ}\)
Subtopic: Self - Inductance |
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A full wave rectifier circuit consists of two \(\mathrm{p\text-n}\) junction diodes, a centre-tapped transformer, capacitor and a load resistance. Which of these components remove the ac ripple from the rectified output?
| 1. | load resistance | 2. | a centre-tapped transformer |
| 3. | \(\mathrm{p\text-n}\) junction diodes | 4. | capacitor |
Subtopic: Rectifier |
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A football player is moving southward and suddenly turns eastward with the same speed to avoid an opponent. The force that acts on the player while turning is:
| 1. | along south-west | 2. | along eastward |
| 3. | along northward | 4. | along north-east |
Subtopic: Newton's Laws |
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The work functions of Caesium \((\mathrm{Cs})\), Potassium \((\mathrm{K})\) and Sodium \((\mathrm{Na})\) are \(2.14~\text{eV}\), \(2.30~\text{eV}\) and \(2.75~\text{eV}\) respectively. If incident electromagnetic radiation has an incident energy of \(2.20~\text{eV}\). which of these photosensitive surfaces may emit photoelectrons?
| 1. | \(\mathrm{Na}\) only | 2. | \(\mathrm{Cs}\) only |
| 3. | Both \(\mathrm{Na}\) and \(\mathrm{K}\) | 4. | \(\mathrm{K}\) only |
Subtopic: Photoelectric Effect: Experiment |
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If \(\oint_s \vec{E} \cdot \overrightarrow{d S}=0\) over a surface, then:
| 1. | the electric field inside the surface is necessarily uniform. |
| 2. | the number of flux lines entering the surface must be equal to the number of flux lines leaving it. |
| 3. | the magnitude of electric field on the surface is constant. |
| 4. | all the charges must necessarily be inside the surface. |
Subtopic: Gauss's Law |
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Given below are two statements:
| Statement I: | Photovoltaic devices can convert optical radiation into electricity. |
| Statement II: | Zener diode is designed to operate under reverse bias in the breakdown. |
| 1. | Statement I is False but Statement II is True. |
| 2. | Both Statement I and Statement II are True. |
| 3. | Both Statement I and Statement II are False. |
| 4. | Statement I is True but Statement II is False. |
Subtopic: Applications of PN junction |
75%
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