Physics Test 64

Result

Physics Test 64

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Question 1
4 / -1

A conducting loop carrying a current I is placed in a uniform magnetic field pointing into the plane of the paper as shown. The loop will have a tendency to

A
Contract

B
Expand

C
Move towards +

D
None of this -

Solution

If we use fleming's left-hand rule. We find that a force is acting in the radially outward direction throughout the circumference of the conducting loop.

Hence, the correct option is (B).
Question 2
4 / -1

A small object of uniform density rolls up a curved surface with an initial velocity v′. It reaches up to a maximum height of 3v² / 4 g with respect to the initial position. The object is

A
Ring

B
Solid sphere

C
Hollow sphere

D
Disc

Solution
Question 3
4 / -1

A long solenoid of diameter 0.1 m has 2×10⁴ turns per metre. At the centre of the solenoid, a coil of 100 turns and radius 0.01 m is placed with its axis coinciding with the solenoid axis. The current in the solenoid reduces at a constant rate to 0A from 4A in 0.05s. If the resistance of the coil is 10π²Ω, the total charge flowing through the coil during this time is.

A
π²

B
32π²

C
4π²

D
32μC

E

Solution
Question 4
4 / -1

If energy E, velocity V, and time T are chosen as the fundamental units, the dimensional formula for surface tension will be

A
EV² T^-2

B
EV^-1 T ^-2

C
EV^-2 T ^-2

D
E² V^-1 T ^-2

Solution
Question 5
4 / -1

An athlete throws a discus from rest to a final angular velocity of 15 rad/s in 0.270 s before releasing it. During acceleration, the discus moves a circular arc of radius 0.810 m. The acceleration of the discus before it is released is ___ ms⁻².

A
45

B
182

C
187

D
192

Solution

ω = ω0+αt

⇒ ω = 0+αt

⇒ α = 15/0.270 rad /s²

Now, a=r,α=0.81×15/ 0.270=45ms⁻²

Hence, the correct option is (A).
Question 6
4 / -1

An AC source of variable frequency f is connected to an LCR series circuit. Which of the following graphs represents the variation of current in the circuit I with frequency f?

A
(A)

B
(B)

C
(C)

D
(D)

Solution

As explainded for frequency 0−fr,Z decrease

Then i=V/Z increases and for frequency fr−∞,Z increases So, i decreases.

Hence, the correct option is (D).
Question 7
4 / -1

A mass M is divided into two parts Xm and (1−X)m. For a given separation, the value of X, for which the gravitational attraction between the two parts becomes maximum, is

A
1/2

B
3/5

C
1/7

D
2/5

Solution
Question 8
4 / -1

A weightless thread can bear tension up to 3.7N. A stone of mass 500g is tied to it and revolved in a circular path of radius 4m in a vertical plane. If ′g′=10m/s⁻², what will be the maximum angular velocity of the stone?

A
2rad / s

B
4rad / s

C
8rad / s

D
16rad / s

Solution
Question 9
4 / -1

An α particle is accelerated through a potential difference of 100V, then the de-Broglie wavelength associated with it is approximately

A
λ = hcV

B
λ = hc.aV

C
λ = hc/aV

D
λ = aV/hc

Solution

Given V=100

Particle nature E=a V .......... (i)

Wave nature E=hμ .......... (ii)

By equation (i) and (ii) we get

aV=hμ

aV=hμ/λ

λ=hc/aV

Hence, the correct option is (C).
Question 10
4 / -1

A metal ball immersed in alcohol weighs W₁ at 0^oC and W₂ at 59^oC. The coefficient of cubical expansion of the metal is less than that of alcohol. If the density of the metal is large compared to that of alcohol, then

A
W₁ > W₂

B
W₁ = W₂

C
W₁ < W₂

D
None of them

Solution

Since it is given that the coefficient of cubical expansion of alcohol is more than that of the metal.

Upthrust = (volume of the metal ball)× (density of liquid)×g

With the increase in temperature volume of the ball will increase and the density of the liquid will decrease. But the coefficient of cubical expansion of liquid is more. Hence the second effect is more dominating. Therefore upthrust, at higher temperatures will be less, or apparent weight will be more.

Hence, the correct option is (C).