UP PGT Physics Mock Test - 9 - UPTET MCQ

Springs deform permanently because of elastic fatigueness. The elasticity of the material of spring is lost and it deforms permanently. 

The speed of any electromagnetic waves in free space is the speed of light c = 3x10⁸ m/s. Electromagnetic waves can have any wavelength λ or frequency f as long as λf = c.

By definition of Electric Field,

When equal charges are given to two spheres of different radii, the potential will be more or the smaller sphere as per the equation, Potential = Charge / Radius.
Since potential is inversely proportional to radius, the smaller radius will have higher potential and vice versa.

A fluid that has no resistance to shear stress is known as an ideal fluid.

Gravitational Potential is dened as the potential energy of a particle of unit mass at that point due to the gravitational force exerted byearth. Gravitational potential energy of a unit mass is known as gravitational potential.

T1=2π√1/g=T, T₂=2π√16/g=4T
(ω1−ω2)t=2π
(2π/T−2π/4T)t=2π
t=4T/3

By faraday's law
ϵ=− dϕ/dt ​=dϕdx​/dx​dt
=B_o​d (2d​/2a)v_o​

The Voltage Transformer can be thought of as an electrical component rather than an electronic component. A transformer basically is very simple static (or stationary) electro-magnetic passive electrical device that works on the principle of Faraday’s law of induction by converting electrical energy from one value to another.
 
The transformer does this by linking together two or more electrical circuits using a common oscillating magnetic circuit which is produced by the transformer itself. A transformer operates on the principles of “electromagnetic induction”, in the form of  Mutual Induction.
Mutual induction is the process by which a coil of wire magnetically induces a voltage into another coil located in close proximity to it. Then we can say that transformers work in the “magnetic domain”, and transformers get their name from the fact that they “transform” one voltage or current level into another.

This is because for maximum diffraction the slit width always equals to the wavelength of light.

Given: Horizontal component (H) = 0.35 G; Angle of dip (δ) = 30^o
Required equation ➔ cosδ= H/B

Therefore, the magnitude of the magnetic field at that place is 0.40 G.

Explanation:

At const volume, 

Q = 500 J

Q=nCPΔT

500=1×2.5×8.31ΔT

ΔT=24.06

W=nRΔT=1×8.31×24.06=200J

T sin θ = mrω²;  r = l sin θ

When a liquid surface meets a solid surface the angle (φ) between the two surfaces is important. In fact a surface will be wetted by water if the angle of contact is less than 90^o, and so waterproofing is designed to produce an angle of contact that is greater than 90^o.

Consider a rod of length l and mass m rotating with an angular velocity of w
dF = dm l w² 
dF = (m/l) dμ l w² 
Integrating
F = ½mlw² 

As the temperature increases, the inter-atomic distance also increases. So, it results in an increase in the area (stress = force /area). As the area increases stress decreases, this results in a decrease in Young's modulus.

PV = constant

 As a bubble comes from bottom to top , the pressure decrease from ( P₀ + ρgh )  to P0

∴  Volume increases and hence radius increases. 

a car battery of 12V provides a current of about 200A, which is the current needed to operate a starter motor. So a battery has a very small internal resistance.
also,The cause of non-correctable battery problems and.A weak cell holds less capacity and is discharged more quickly.

Every point on a wave-front may be considered a source of secondary spherical wavelets which spread out in the forward direction at the speed of light. The new wave-front is the tangential surface to all of these secondary wavelets.

According to Huygens' principle, a plane light wave propagates though free space at the speed of light, c. The light rays associated with this wave-front propagate in straight-lines. It is also fairly straightforward to account for the laws of reflection and refraction using Huygens' principle.

Zeros occurring between non zero digits also contribute to the number accuracy and thus all the digits that contribute towards the accuracy of the number are considered significant.

In case of semiconductor Resistivity∝1​/temperature
In this case as temperature increases electrons jump to conduction band resistance decreases R∝ρ(Resistivity) so resistivity also decreases and current increases.
Vibration of electrons increases with rise in temperature and hence collision between ions and electrons increases with temperature.

Here V_p=220V V_s=110V
As we know the relation between V and n,
As,
V_e/V_s=n_p/ns ->220/110
Np/ns=2/1=2:1
Therefore, no. of turns in primary is greater than no. of turns in secondary,
Hence, it is a step-down transformer.

A temperature gradient is a physical quantity that describes in which direction and at what rate the temperature changes the most rapidly around a particular location.
The temperature gradient is a dimensional quantity expressed in units of degrees per unit length.
The SI unit is kelvin per meter.
Expression: ∆T/∆x, where ∆T = change in temperature and ∆x = change in distance

It is not possible to remove or add protons/neutrons to an atom, but electrons can be added or removed by an atom easily.
By adding electrons it becomes negatively charged.
By removing electrons it becomes positively charged. 

[P] = [F/A] = MLT^-2 / L²  = ML^-1T^-2
[F/V] = MLT^-2 / L3  = ML^-2T^-2
[E/V] = ML²T^-2 / L³  = ML^-1T^-2

The two physical quantities which do not have the same dimensions can’t be added or subtracted in the same expression because doing so would lead to equating two quantities of different dimensions, which is non possible. Ex [F]  [P].

The image height formed by the objective lens of a telescope can be found using the concept of angular magnification.

For distant objects, the angular size (α) of the object as seen by the lens is approximately α = height of the object / distance to the object = 10 / 2000 = 0.005 radians.

The image of the object is formed at the focal plane of the objective lens, so the height of the image (h') is given by h' = focal length × angular size = 1.2 × 0.005 = 0.006 meters.

Converting to millimeters: 0.006 meters = 6 mm.
Therefore, the height of the image of the tower formed by the objective is 6 mm.

There are three rules on determining how many significant figures are in a number: 

• Non-zero digits are always significant.
• Any zeros between two significant digits are significant.
• A final zero or trailing zeros in the decimal portion ONLY are significant.

Keeping these rules in mind, we can say that there are 5 significant digits.

A velocity time graph represents the velocity of an object at a very certain time. If two curves collide that means that their velocities at the given time are equal. Their acceleration may or may not be equal depending upon the slope of the curve at the point of intersection.

for hot reservoir I.e. source
temperature T₁=400k
heat supplied Q₁=800J
For cold reservoir i.e. sink
Temperature T₂=?
Heat supplied Q₂=640J
According to carnot’s theorem,
Q₁/Q₂= T₂/T₁
640/800= T₂/400
T₂=320k