CBSE 11TH PHYSICS - Online Test
Q1. At large flow velocities the flow of a fluid becomes
Answer : Option B
Explaination / Solution:
When any liquid is flowing more than the velocity of it's critical velocity then flow becomes turbulent.
Q2. The number of degrees of freedom a monatomic molecule is
Answer : Option A
Explaination / Solution:
Degrees of freedom of a system refers to the possible independent motions a system can have.
Monoatomic gas molecule can have 3 independent motion and hence have 3 degrees of freedom (all are translational).
Q3. Animal and plant life in lakes and ponds are not destroyed because
Answer : Option D
Explaination / Solution:
As and when water is cooled down to its freezing point the thickness T of the ice layer increases. The increase in thickness of ice decreases the rate of cooling of water and thus freezing process slows down.
Q4. Percentage error δa is given by
Answer : Option D
Explaination / Solution:
Percentage Error: It is the relative error measured in percentage.
So Percentage Error
%
Q5. Damping is due to
Answer : Option B
Explaination / Solution:
Damping is proportional to the velocity of the mass through the medium , so it can be said that air drag ,friction offers damping.
Q6. The acceleration due to gravity at a depth d in terms of g the acceleration due to gravity at radius of the earth is
Answer : Option D
Explaination / Solution:
Acceleration due to gravity at the surface of the earth of radius RE
-(1)
Acceleration due to gravity at depth d from the surface of the earth
-(2)
From (1) & (2), we get
Q7. If the position- time graph is a straight line
Answer : Option D
Explaination / Solution:
The principle is that the slope of the line on a position-time graph reveals useful information about the velocity of the object.
If the velocity is constant, then the slope is constant (i.e., a straight line).
Q8. If y(x, t) = a sin (kx + ωt + φ ) represents a wave function then ‘φ’ is
Answer : Option D
Explaination / Solution:
In the equation
y(x, t) = a sin (kx + t + )
The term represents initial phase or epoch
Hence the term is initial phase
Q9. For a ball dropped from a tower of height h the total mechanical energy is
Answer : Option C
Explaination / Solution:
mechanical energy = sum of potential and kinetic energies
a falling ball will have both these energies in between topmost and bottomost points of its motion so mechanical energy is the sum of potential and kinetic energies.
Q10.
If are components of vectors A and B along the x and y axis then the sum of the vectors A and B has a component in the x direction equal to
Answer : Option B
Explaination / Solution:
The component method of addition can be summarized this way:
- Using trigonometry, find the x-component and the y-component for each vector.
- Add up both x-components, (one from each vector), to get the x-component of the total.
- Add up both y-components, (one from each vector), to get the y-component of the total.
- Add the x-component of the total to the y-component of the total, and then use the Pythagorean theorem and trigonometry to get the size and direction of the total.
Using these points in mind, the sum of the vectors A and B has a component in the x direction
