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Under Graduate Entrance Exams NEET Entrance Exam Physics TEST : 109

Under Graduate Entrance Exams NEET Entrance Exam # Physics Nuclei Prepare / Learn

Q1. When a hydrogen bomb explodes, which of the following is used?

A. both

B. neither of two

C. fission

D. fusion

Answer : Option A
Explaination / Solution:
No Explaination.

Under Graduate Entrance Exams NEET Entrance Exam # Physics Thermal Properties of Matter Prepare / Learn

Q2.

The electrical resistance in ohms of a certain thermometer varies with temperature according to the approximate law : R =R $_{o}$ [1 + $α$ (T –T $_{o}$ )] The resistance is 101.6 $Ω$ at the triple-point of water 273.16 K, and 165.5 $Ω$ at the normal melting point of lead (600.5 K). What is the temperature when the resistance is 123.4 $Ω$ ?

A. 404.8 K

B. 364.8 K

C. 384.8 K

D. 344.8 K

Answer : Option C
Explaination / Solution:

It is given that:
R = R0 [1 +

α

(T – T0)] … (i)

where,
R0 and T0 are the initial resistance and temperature respectively

R and T are the final resistance and temperature respectively

α

is a constant
At the triple point of water, T0 = 273.15 K
Resistance of lead, R0 = 101.6

Ω

At normal melting point of lead, T = 600.5 K
Resistance of lead, R = 165.5

Ω

Substituting these values in equation (i), we get:
R = Ro [1 +

α

(T – To)]
165.5 = 101.6 [ 1 +

α

(600.5 - 273.15) ]
1.629 = 1 +

α

(327.35)
∴

α

= 0.629 / 327.35 = 1.92 × 10-3 K-1

For resistance, R1 = 123.4

Ω

R1 = R0 [1 +

α

(T – T0)]
where,
T is the temperature when the resistance of lead is 123.4

Ω

123.4 = 101.6 [ 1 + 1.92 × 10-3( T - 273.15) ]
Solving for T, we get
T = 384.8 K.

Under Graduate Entrance Exams NEET Entrance Exam # Physics Units and Measurements Prepare / Learn

Q3. The number of significant digits in 0.007 is

A. 4

B. 1

C. 2

D. 3

Answer : Option B
Explaination / Solution:

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.

So keeping these rules in mind, there are 1 significant digit.

Under Graduate Entrance Exams NEET Entrance Exam # Physics Alternating Current Prepare / Learn

Q4. The voltage across the terminals of an ac power supply varies with time according to Vcosωt. The voltage amplitude is V = 45.0 V. Average potential difference between the two terminals of the power supply is

A. 33.8 V

B. zero V

C. 35.8 V

D. 37.8 V

Answer : Option B
Explaination / Solution:

average value of ac voltage for a half cycle is positive and similiarly the mean value of ac voltage for other half cycle is negative.

Average potential difference between the two terminals for complete full cycle

$V_{a v} = (0.637 V_{0}) + (- 0.637 V_{0}) = 0$

Under Graduate Entrance Exams NEET Entrance Exam # Physics Current Electricity Prepare / Learn

Q5. The wire of the potentiometer has resistance 4 ohms and length 1 m. It is connected to a cell of e.m.f. 2 volts and internal resistance 1 ohm, the potential gradient in the potentiometer wire is:

A. 0.8 volt/m

B. 2.0 volt/m

C. 1.2 volt/m

D. 1.6 volt/m

Answer : Option D
Explaination / Solution:

If the battery has an e.m.f E, resitance of the potentiometer is R and the internal resistance of the battery is r, then the current I flowing in the potentiometer wire is given as,

$\begin{array}{l} I = \frac{E}{(R + r)} \\ I = \frac{2}{(4 + 1)} \\ I = 0.4 A \end{array}$

The potential difference V across the potentiometer,

$\begin{array}{l} V = I \times R \\ \Rightarrow V = 0.4 \times 4 \\ V = 1.6 V \end{array}$

The potential gradient = ( potential drop across the potentiometer)/ length of the potentiometer wire)

= V/l

= 1.6/1

Potential gradient = 1.6 V/m

Under Graduate Entrance Exams NEET Entrance Exam # Physics Oscillations Prepare / Learn

Q6. A mass M is suspended from a spring of negligible mass. The spring is pulled a little and then released so that the mass executes simple harmonic oscillations with a time period T.

A. 9/ 16

B. 5/ 4

C. 25/ 16

D. 41369.0

Answer : Option D
Explaination / Solution:
No Explaination.

Under Graduate Entrance Exams NEET Entrance Exam # Physics Moving Charges and Magnetism Prepare / Learn

Q7. If number of turns, area and current through a coil is given by n, A and i respectively then its magnetic moment will be

A. ni

\sqrt{A}

B. niA2

C. n2iA

Answer : Option D
Explaination / Solution:

The magnetic moment associated with a coil carrying current is given by the product of its area and the current through it. M=n I A

Under Graduate Entrance Exams NEET Entrance Exam # Physics Wave Optics Prepare / Learn

Q8. In a two-slit interference experiment in which the slits are 0.200 mm apart and the screen is 1.00 m from the slits. The m = 3 bright fringe is 9.49 mm from the central fringe. Wavelength of the light is

A. 633 nm

B. 653 nm

C. 663 nm

D. 683 nm

Answer : Option A
Explaination / Solution:
No Explaination.

Under Graduate Entrance Exams NEET Entrance Exam # Physics Magnetism and Matter Prepare / Learn

Q9. Correct unit of Bohr magneton is

A. J

B. J/T

C. T

D. T/J

Answer : Option B
Explaination / Solution:
No Explaination.

Under Graduate Entrance Exams NEET Entrance Exam # Physics Electronic Devices Prepare / Learn

Q10. Electrons are forbidden in a band (in a crystal) called the

A. forbidden band

B. valence band

C. conduction band

D. Memory band

Answer : Option A
Explaination / Solution:

A region of values of energy that electrons in an ideal crystal (without defects) cannot have. In semiconductors the forbidden band separating the valence band and the conduction band is usually considered. In this case the energy difference between the lower level (bottom) of the conduction band and the upper level (ceiling) of the valence band is called the width of the forbidden band.

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Under Graduate Entrance Exams NEET Entrance Exam Physics TEST : 109