Physics - Online Test
Q1. The sun releases energy coming from
Answer : Option B
Explaination / Solution:
In addition to intense heat, there is an incredible amount of pressure at the Sun's core. In fact, the vast amounts of hydrogen atoms in the Sun's core are compressed and heated so much that they fuse together.
This reaction, known as nuclear fusion, converts hydrogen atoms into helium. The by-product of nuclear fusion in the Sun's core is a massive volume of energy that gets released and radiates outward toward the surface of the Sun and then into the solar system beyond it.
Q2. A ring of radius r and mass m rotates about its central axis. The kinetic energy is
Answer : Option C
Explaination / Solution:
Q3. An air bubble of radius r is formed inside a tank of water of depth h. The atmospheric pressure is equal to a water column of height H. the pressure inside the bubble is
Answer : Option C
Explaination / Solution:
No Explaination.
Q4. A cylinder contains a mixture of helium and argon gas in equilibrium at 150C. What is the average kinetic energy for each type of gas molecule?
Answer : Option A
Explaination / Solution:
Average KE depends only on temperature
Q5. A person with defective eyesight is unable to see objects clearly nearer than 1.5 m. He wants to read a book placed at a distance of 30 cm from his eyes. Find the power of the lens he requires for his spectacles
Answer : Option B
Explaination / Solution:
No Explaination.
Q6. The energy released when 1 a.m.u. of mass is completely converted into energy is
Answer : Option B
Explaination / Solution:
No Explaination.
Q7. A ‘thermacole’ icebox is a cheap and efficient method for storing small quantities of cooked food in summer in particular. A cubical icebox of side 30 cm has a thickness of 5.0 cm. If 4.0 kg of ice is put in the box, estimate the amount of ice remaining after 6 h. The outside temperature is 45 C, and co-efficient of thermal conductivity of thermacole is 0.01 J . [Heat of fusion of water = 335 ]
Answer : Option D
Explaination / Solution:
A = Surface area of the box = 6s2 = 6 × (0.3)2 = 0.54 m3
Time gap, t = 6 h = 6 × 60 × 60 s
But Q = m'L
∴ m' = Q/L
= 104976/(335 × 103) = 0.313 kg
Mass of ice left = 4 – 0.3 = 3.7 kg
Hence, the amount of ice remaining after 6 h is 3.7 kg.
Q8. The mass of a box measured by a grocer’s balance is 2.300 kg. Two gold pieces of masses 20.15 g and 20.17 g are added to the box. What is the difference in the masses of the pieces to correct significant figures?
Answer : Option D
Explaination / Solution:
Difference in masses = 20.17 – 20.15 = 0.02 g
In subtraction, the final result should retain as many decimal places as there are in the number with the least decimal places.
Q9. Domestic power supply in India is
Answer : Option B
Explaination / Solution:
India use ac power supply of frequency 50 Hz and voltage 230V while America uses ac supply of frequency 60Hz and voltage 110V.
Q10. The period of a simple pendulum is doubled when
Answer : Option C
Explaination / Solution:
No Explaination.
