Physics 2018 | Study Mode

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Question 31
A
\(1.11\times 10^{-7} N\) towards P
B
\(1.11\times 10^{-7} N\) towards Q
C
\(9.26\times 10^{-8} N\) towards P
D
\(9.26\times 10^{-8} N\) towards Q
Explanation

\(F= \frac{Gm_{1}m_{2}}{r^{2}}\)

\(m_{1} = 100kg\)

\(m_{2} = 20kg; r =1.2m\)

\(G= 6.67\times 10^{-11}\)

\(F = \frac{6.67\times 10^{-11}\times 100\times 20}{(1.2)^{2}} = 9.26\times 10^{-8}\)

The acceleration of each object is inversely proportional to the mass, the lighter object will move a bit faster, hence. the force will act in the direction of Q.


Correct option: D
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Question 32
A
50V
B
100V
C
200V
D
400V
Explanation

The ideal transformer (either step-up or step-down) works with the equation:

\(\frac{V_{s}}{V_{p}} = \frac{N_{s}}{N_{p}} = \frac{I_{p}}{I_{s}}\)

where \(V_{s}\) and \(V_{p}\) are the voltages applied to the secondary and the primary respectively

\(N_{s}\) and \(N_{p}\) are the number of turns on the secondary and primary coils respectively

\(I_{p}\) and \(I_{s}\) are the currents flowing in the primary and secondary coils respectively.

\(\frac{V_{s}}{100} = \frac{200}{100}\)

\(V_{s} = \frac{200\times 100}{100} = 200V\)


Correct option: C
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Question 33
A
increases
B
decreases
C
remain the same
D
decreases and later increases
Explanation

The velocity ratio and therefore, the mechanical advantage of an inclined plane system increases as \(\theta\) decreases and vice-versa.


Correct option: B
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Question 34
A
doubled
B
quartered
C
halved
D
quadrupled
Explanation

Given \(K_{1}\) = \(\frac{mv^{2}}{2}\).

When v is halved, we have

\(K_{2}\) = \(\frac{m\times (\frac{v}{2})^{2}}{2}\)

= \(\frac{K_{1}}{4}\)

Hence, the initial kinetic energy is quartered.


Correct option: B
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Question 35
A
250\(ms^{-1}\)
B
625\(ms^{-1}\)
C
1200\(ms^{-1}\)
D
1500\(ms^{-1}\)
Explanation

The fundamental frequency \((f_{0})\) = \(\frac{v}{2l}\)

\(f_{0} = 150Hz; l =400cm = 4m\)

\(150 = \frac{v}{2\times 4}\)

\(v = 150 \times 8 = 1200ms^{-1}\)


Correct option: C
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Question 36
A
4
B
3\(\frac{1}{2}\)
C
2\(\frac{1}{2}\)
D
2
Explanation

Explanation not provided, please join discuss, your contributions are welcomed


Correct option: C
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Question 37
A
resistance box
B
standard resistor
C
shunt resistor
D
multiplier resistor
Explanation

Explanation not provided, please join discuss, your contributions are welcomed


Correct option: B
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Question 38
A
The electrolyte does not need attention
B
It can be recharged
C
It has low internal resistance
D
It has a much longer life than lead-acid accumulator
Explanation

Explanation not provided, please join discuss, your contributions are welcomed


Correct option: A
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Question 39
A
live, neutral and earth
B
neutral, earth and live
C
earth, live and neutral
D
earth, neutral and live
Explanation

Explanation not provided, please join discuss, your contributions are welcomed


Correct option: B
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Question 40
A
I only
B
I and II only
C
II and III only
D
I, II and III
Explanation

Capacitors pass AC but block DC signals (when charged up to the applied DC voltage), they are often used to separate the AC and DC components of a signal. Capacitors are also primarily used to store energy.


Correct option: C

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