Physics Test 208

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Physics Test 208

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Weekly Quiz Competition

Question 1
4 / -1

Which one of the following statements about the atomic nucleus is accurate?

A
The nucleus is held together mostly by the electrical and gravitational forces

B
Large nuclei are denser than light nuclei

C
All nuclei have nearly the same density

D
Smaller nuclei are denser than larger nuclei

Solution

Most nuclei are approximately spherical. The average radius of a nucleus with A nucleons is R = R₀A^1/3, where R⁰ = 1.2*10^-15 m. The volume of the nucleus is directly proportional to the total number of nucleons. This suggests that all nuclei have nearly the same density.
Question 2
4 / -1

The quantization of charge has little practical consequence and can be ignored at the

A
microscopic level

B
macroscopic level

C
all levels

D
information given is insufficient to decide

Solution

Gain or loss of charge in terms of few electrons each carrying very small charge is unobservable at macroscopic level.
Question 3
4 / -1

What is the de-Broglie wavelength associated with an electron accelerated through a potential of 100 volts?

A
12.3 nm

B
0.122 nm

C
123 nm

D
1.23 nm

Solution
Question 4
4 / -1

Given N resistors each of resistance R are first combined to get minimum possible resistance and then combined to get maximum possible resistance. The ratio of the minimum to maximum resistance is

A
N

B
N²

C
1/N²

D
1/N
Solution
The problem involves combining N resistors of resistance R:
- Minimum Resistance: Connect all resistors in parallel.
  
  Formula: R_min = R/N
- Maximum Resistance: Connect all resistors in series.
  
  Formula: R_max = N×R
Calculate the ratio of minimum to maximum resistance:
- Ratio: (R/N) / (N×R)
- Simplified: 1/N²
Question 5
4 / -1

When a negatively charged conductor is connected to earth,

A
No charge flow occurs.

B
Protons flow from the conductor to the earth.

C
Electrons flow from the earth to the conductor.

D
Electrons flow from the conductor to the earth.

Solution

Explanation:

When a negatively charged conductor is connected to the earth, electrons will flow from the conductor to the earth. This is because electrons have a negative charge and they will be repelled from the negatively charged conductor and attracted to the positively charged earth. As electrons flow from the conductor to the earth, the negative charge on the conductor will gradually decrease until it becomes neutral.

Option A is incorrect because charge flow does occur when a negatively charged conductor is connected to the earth.

Option B is incorrect because protons have a positive charge and they are not free to move in a conductor.

Option C is incorrect because electrons flow from the earth to the conductor, not the other way around.
Question 6
4 / -1

According to the standard convention, the electric potential at a point infinitely far from a charge is taken to be:

A
Unity

B
May be zero or infinite

C
Zero

D
Infinite
Solution
The standard convention states that the electric potential at a point infinitely far from a charge is considered to be:
- Zero
This means that as you move further away from a charge, the potential energy associated with that charge diminishes to zero.
Question 7
4 / -1

Photon has a charge of

A
-2e; e= charge on electron

B
+2e; e= charge on electron

C
zero

D
-e; e= charge on electron

Solution

A photon is massless, has no electric charge, and is a stable particle. In vacuum, a photon has two possible polarization states. The photon is the gauge boson for electromagnetism, and therefore all other quantum numbers of the photon (such as lepton number, baryon number, and flavour quantum numbers) are zero.
Question 8
4 / -1

Artificial disintegration with alpha particles of which of the following led to the discovery of neutron?

A
Be

B
Na

C
N

D
Ba

Solution

James Chadwick set up an experiment to test his hypothesis. Chadwick put a piece of beryllium in a vacuum chamber with some polonium. The polonium emitted alpha rays, which struck the beryllium. When struck, the beryllium emitted the mysterious neutral rays.
Question 9
4 / -1

Three resistors of 4Ω, 12Ω , and 6Ω are connected in parallel. No. of 12Ω resistors required to be connected in parallel to reduce the total resistance to half of its original is

A
6

B
3

C
12

D
2

Solution

Here 4 Ω, 12 Ω, 6 Ω when connected in parallel results in 2Ω. to reduce it to half we have to join 1\R original = 6\12 for reducing it to half we have to join 6 , 12 Ω resistors in parallel (6\12) + (1\ 12 × 6) = 12\12 = 1 ohm . Half of its original value therefore option a is correct.
Question 10
4 / -1

Three identical cells, each of 4 V and internal resistance r, are connected in series to a 6 ohm resistor. If the current flowing in the circuit is 2 A. The internal resistance of each cell is

A
0.11 ohm

B
0 ohm

C
0. 12 ohm

D
1.1 ohm

Solution

Total emf = 3 x 4 = 12 V

Total resistance = 6 + 3r

Current in the circuit = 2 A

Using ohm's law

2 = 12/ (6+3r)

2(6+3r)=12

12+6r=12

6r = 12-12 = 0

r = 0/6 = 0

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Re-Attempt Weekly Quiz Competition

Physics Test 208

Result

Physics Test 208

Score

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Rank

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Question 1

The nucleus is held together mostly by the electrical and gravitational forces

Large nuclei are denser than light nuclei

All nuclei have nearly the same density

Smaller nuclei are denser than larger nuclei

Solution

Question 2

microscopic level

macroscopic level

all levels

information given is insufficient to decide

Solution

Question 3

12.3 nm

0.122 nm

123 nm

1.23 nm

Solution

Question 4

N

N2

1/N2

1/N

Solution

Question 5

No charge flow occurs.

Protons flow from the conductor to the earth.

Electrons flow from the earth to the conductor.

Electrons flow from the conductor to the earth.

Solution

Question 6

Unity

May be zero or infinite

Zero

Infinite

Solution

Question 7

-2e; e= charge on electron

+2e; e= charge on electron

zero

-e; e= charge on electron

Solution

Question 8

Be

Na

N

Ba

Solution

Question 9

6

3

12

2

Solution

Question 10

0.11 ohm

0 ohm

0. 12 ohm

1.1 ohm

Solution

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N²

1/N²