Question 81 : Ultrasound devices operate with minimum frequency from
1. 20kHz
2. 35 kHz
3. 45 kHz
4. 60 kHz
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Question 82 : Which one is not a part of Kepler's Law
1. Law of orbits
2. Law of areas
3. Law of speed
4. Law of periods
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Question 83 : The speed of sound travel fastest through
1. Liquid
2. Solid
3. Gas
4. None of the above
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Question 84 : Who is known as the 'father of quantum theory'
1. Albert Einstein
2. Max Planck
3. Werner Heisenberg
4. Ernest Rutherford
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Question 85 : Who gave black hole theory
1. Albert Einstein
2. Stephen Hawking
3. Isaac Newton
4. None of the above
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Question 86 : Which physicists is the writer of the book 'A Brief History of Time'
1. Isaac Newton
2. Hans Bethe
3. Albert Einstein
4. Stephen Hawking
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Question 87 : The unit of intensity of electric field is
1. N/c
2. N/m
3. J/c
4. volt
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Question 88 : The energy of a photon varies directly with its
1. Wave length
2. Frequency
3. Speed
4. None of the above
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Question 89 : According to the quantum theory of light, the energy of light is carried in discrete units are called
1. Photoelectrons
2. Protons
3. Electrons
4. Photons
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Question 90 : Who discovered X-ray
1. Marie Curie
2. Pierre Curie
3. Wilhelm Rontgen
4. Ernest Rutherford
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