A closely wound solenoid of 2000 turns and area of cross-section 1.5 × 10–4 m2 carries a current of 2.0 A. It is suspended through its centre and perpendicular to its length, allowing it to turn in a horizontal plane in a uniform magnetic field 1.5 × 10–2 T , making an angle of 30° with the axis of the solenoid. The torque on the solenoid will be?
1. 3 × 10–3 N-m
2. 4.5 × 10–3 N-m
3. 1.5 × 10–2 N-m
4. 3 × 10–2 N-m
Subtopic: Current Carrying Loop: Force & Torque |
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A freshly prepared radioactive source of half-life 2 h emits radiation of intensity which is 64 times the permissible safe level. Calculate, the minimum time after which it would be possible to work safely with this source.
1. 12 h
2. 24 h
3. 6 h
4. 130 h
Subtopic: Radioactivity (OLD NCERT) |
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A ball is dropped from a high rise platform t = 0 starting from rest. After 6 s another ball is thrown downwards from the same platform with a speed v . The two balls meet at t = 18 s. What is the value of v?
1. 74 m/s
2. 64 m/s
3. 84 m/s
4. 94 m/s
Subtopic: Distance & Displacement |
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The thermo emf E (in volts) of a certain thermocouple is found to vary with Q (in C) according to equation 
where Q is temperature of the hot function being kept at 0 °C. Then, the neutral temperature of the thermocouple is
where Q is temperature of the hot function being kept at 0 °C. Then, the neutral temperature of the thermocouple is1. 300 ° C
2. 400 ° C
3. 100 ° C
4. 200 ° C
Subtopic: Calorimetry |
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The maximum vertical distance through which is fully dressed astronaut can jump on the earth is 0.5 m. Estimate the maximum vertical distance through which he can jump on the moon, which has a mean density 2/3 rd that of the earth and radius one quarter that of the earth.
1. 1.5 m
2. 3 m
3. 6 m
4. 7.5 m
Subtopic: Gravitational Potential Energy |
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If there were a reduction in gravitational effect, which of the following forces do you think would change in some respect?
1. Magnetic force
2. Electrostatic force
3. Viscous force
4. Archimedes's uplift
Subtopic: Newton's Law of Gravitation |
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Two batteries of emf 4 v and 8 V with internal resistance 1Ω and 2Ω respectively are connected to an external resistance R = 9Ω as shown in figure. The current in circuit and the potential difference between P and Q respectively will be
1. 
Subtopic: EMF & Terminal Voltage |
61%
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A body at a temperature of 728 ° C and has surface area 5 cm2, radiates 300 J of energy each minute. The emissivity is
(given Boltzmann constant
)
(given Boltzmann constant
)1. e = 0.18
2. e = 0.02
3. e = 0.2
4. e = 0.15
Subtopic: Stefan-Boltzmann Law |
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