CBSE 11TH PHYSICS - Online Test

Answer : Option C
Explaination / Solution:

The law of equipartition of energy sates that for any dynamical system in a thermal equilibrium, the total energy is equally divided among the degrees of freedom. The energy associated with a molecule for one degree of freedom is 12 kBT

Answer : Option C
Explaination / Solution:

Alcohal has higher coefficient of volume expansion in comparison to glass and Invar.

Answer : Option C
Explaination / Solution:

Mean is the average of all numbers. So mean of all the absolute errors will be given by sum of all absolute errorsnumber of errors$\frac{sumofallabsoluteerrors}{numberoferrors}$

 

Answer : Option B
Explaination / Solution:

Torque;τ=Iα,a= angular accleration

τ=−mglsinθ∴α≃mglθI

α=−ω2θω=mglI−−−√

so Time period T is :

T = 2π
  Imgl−−−√

Answer : Option D
Explaination / Solution:

The value of G was experimentally determined by Lord Henry Cavendish using a torsion balance.Cavendish brought two large lead spheres near the smaller spheres attached to the rod. Since all masses attract, the large spheres exerted a gravitational force upon the smaller spheres and twisted the rod a measurable amount. Once the torsional force balanced the gravitational force, the rod and spheres came to rest and Cavendish was able to determine the gravitational force of attraction between the masses.Cavendish expressed his result in terms of the density of the Earth.

G=gR2earthMearth=3g4πRearthρearth

After converting to SI units, Cavendish's value for the Earth's density, 5.448 g cm−3, gives

G = 6.74×10−11 m3 kg–1 s−2

Today, the currently accepted value is 6.67259 x 10-11 N m2/kg2.

Answer : Option A
Explaination / Solution:

Instantaneous velocity is the velocity of an object in motion at a specific point in time. This is determined similarly to average velocity, but we narrow the period of time so that it approaches zero.

The formula for instantaneous velocity is the limit as t approaches zero of the change in position over the change in t.

Mathematically,

limt→0ΔxΔt

Where x is the given function with respect to time t. The Instantaneous Velocity is expressed in m/s.

Answer : Option D
Explaination / Solution:

In the equation 

y(x, t) = a sin (kx + ωt + φ )

the term with distance travelled 'x' is called angular wave number or propagation constant

Hence k is the angular wave number.

Answer : Option A
Explaination / Solution:

A force is said to be conservative if work done by this force is independent of path and is dependent only on end points .

Answer : Option D
Explaination / Solution:

Torque = Force x Perpendicular distance of the line of action of the force from the axis of rotation. It is also called moment of force.

 torque is defined as the cross product of the vector by which the force's application point is offset relative to the fixed suspension point (distance vector) and the force vector, which tends to produce rotational motion.

τ⃗ =r⃗ ×F⃗ 

Answer : Option D
Explaination / Solution:

A unit vector in a normed vector space is a vector (often a spatial vector) of length 1. A unit vector is often denoted by a lowercase letter with a circumflex, or "hat": i^ (pronounced "i-hat"). The term direction vector is used to describe a unit vector being used to represent spatial direction.

i^=a unit vector directed along the positive x axis

j^= a unit vector directed along the positive y axis

k^ = a unit vector directed along the positive z axis