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NEET Practice Test - 6 - NEET MCQ


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30 Questions MCQ Test - NEET Practice Test - 6

NEET Practice Test - 6 for NEET 2024 is part of NEET preparation. The NEET Practice Test - 6 questions and answers have been prepared according to the NEET exam syllabus.The NEET Practice Test - 6 MCQs are made for NEET 2024 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests for NEET Practice Test - 6 below.
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NEET Practice Test - 6 - Question 1

A conducting sphere of radius 10 cm is charged with 10 μC. Another uncharged sphere of radius 20 cm is allowed to touch it for some time. After that if the spheres are separated, then surface density of charges on the spheres will be in the ratio

Detailed Solution for NEET Practice Test - 6 - Question 1
When the charged sphere in contact with uncharged sphere, the charge will flow till the potential at the surface of the spheres become same.

Let the radius of the charged sphere is r1 and charge density σ1 and charge on it be q1 and the radius of the uncharged sphere is r2 and charge density σ2 and charge on it be q2 after both are in contact with each other.

Charge density

Hence,

NEET Practice Test - 6 - Question 2

A capacitor of capacitance 2 μF is connected in the tank circuit of an oscillator oscillating with a frequency of 1 kHz. If the current flowing in the circuit is 2 mA, the voltage across the capacitor will be

Detailed Solution for NEET Practice Test - 6 - Question 2

Reactance of capacitor or capacitive reactance is given by:

; where f is frequency of the alternating current.

Given: f = 1 × 103 Hz, C = 2 × 10–6 F

Hence, voltage across the capacitor,

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NEET Practice Test - 6 - Question 3

Two infinitely long parallel conducing plates having surface charge densities +σ and –σ are separated by a small distance. The medium between the plates is vacuum. If Ɛ0 is the dielectric permittivity of vacuum, then the electric field in the region between the plates is

Detailed Solution for NEET Practice Test - 6 - Question 3
It is given that conducting plates have surface charge densities +σ and –σ. Since the sheet is large, the electric field E at energy point near the sheet will be perpendicular to the sheet.

The resultant electric field is given by:

E' = E + E = 2E

If σ is surface charge density, then

Electric field,

Hence, E' = 2E = V/m

NEET Practice Test - 6 - Question 4

The magnetic moment of current (I) carrying circular coil of radius (r) and number of turns (n) varies as:

Detailed Solution for NEET Practice Test - 6 - Question 4
The magnetic moment is a measure of the strength of a magnetic source. The equation for magnetic moment in the current carrying loop, carrying current I and of area vector A is given by

M = IA

Here, I is current and A is area (= πr2).

M = I πr2

M ∝ r2

Note: Magnetic moment and magnetic dipole moment are the same thing.

NEET Practice Test - 6 - Question 5

An electric current passes through a long straight wire. At a distance 5 cm from the wire, the magnetic field is B. The field at a distance 20 cm from the wire would be

Detailed Solution for NEET Practice Test - 6 - Question 5
For a long straight wire,

Magnetic field, B =

When r = 5 cm,

B = …(i)

Similarly, when r = 20 cm,

B' = …(ii)

From (i) and (ii), we get

B' = B/4

NEET Practice Test - 6 - Question 6

In a detector, output circuit consists of R = 10kΩ and C = 100 pF. The frequency of carrier signal it can detect is

Detailed Solution for NEET Practice Test - 6 - Question 6
Here, R = 10kΩ and C = 104Ω

C = 100 pF = 10–10 F

Time constant of the circuit,

For demodulation,

or

or

Therefore, the frequency of carrier signal must be much greater than 1 MHz.

NEET Practice Test - 6 - Question 7

Four resistances 10Ω, 5Ω, 7Ω and 3Ω are connected, so that they form the sides of a rectangle AB, BC, CD and DA, respectively. Another resistance of 10Ω is connected across the diagonal AC. The equivalent resistance between A and B is

Detailed Solution for NEET Practice Test - 6 - Question 7
3Ω resistor and 7Ω resistor are in series.

Therefore, resultant = 10Ω (7 + 3)

This 10Ω equivalent resistance is in parallel with resistance (10Ω) in arm AC.

⇒ R1 = 5Ω

Again R2 is in parallel with resistance (10Ω) in arm AB.

⇒ R = 5Ω

NEET Practice Test - 6 - Question 8

In an experiment of finding the focal length of a concave mirror, a graph is drawn between the magnitudes of u and v. The graph looks like:

Detailed Solution for NEET Practice Test - 6 - Question 8
In case of concave mirror, when we move the object from infinity to focus of the mirror (i.e. u decreases from ∞ to f), the image moves from focus to (i.e. v increases from f to ∞). Therefore, the graph looks like the curve shown in Fig. (3).
NEET Practice Test - 6 - Question 9

A photon of energy 4 eV is incident on a metal surface whose work function is 2 eV. The minimum reverse potential to be applied for stopping the emission of electrons is

Detailed Solution for NEET Practice Test - 6 - Question 9
Key Idea: Kinetic energy of photoelectron is eV0; where V0 is stopping potential.

From Einsteins photoelectric equation,

Here, EK is maximum kinetic energy of electron, v is frequency and W is work function.

= 4 eV – 2 eV = 2 eV

But = eV0; where V0 is stopping potential.

Thus, eV0 = 2 eV

V0 = 2 V

NEET Practice Test - 6 - Question 10

The work function of a substance is 4.0 eV. The longest wavelength of light that can cause photoelectron emission from this substance is approximately

Detailed Solution for NEET Practice Test - 6 - Question 10
The minimum energy of incident radiation required to eject the electrons from metallic surface is defined as work function of that surface.

W0 = hc0 ; where λ0 = threshold wavelength.

Work function in electron volt W0 (eV),

⇒ λ0 = 310 nm

NEET Practice Test - 6 - Question 11

The function of heavy water in a nuclear reactor is to

Detailed Solution for NEET Practice Test - 6 - Question 11
A nuclear reactor is a device in which a self-sustaining controlled chain reaction is produced in a fissionable material. A nuclear reactor consists of a moderator which is used to slow down the neutrons. Heavy water is the best moderator.
NEET Practice Test - 6 - Question 12

Which of the following logic gates is an universal gate?

Detailed Solution for NEET Practice Test - 6 - Question 12
The NAND gate and the NOR gate can be said to be universal gates since combinations of them can be used to accomplish any of the basic operations and can thus produce an inverter, an OR gate, or an AND gate. The non-inverting gates do not have this versatility since they can't produce an invert.

Note: The basic symbol and truth table of NAND gate are shown below:

NEET Practice Test - 6 - Question 13

Which of the following pairs does not have similar dimensions?

Detailed Solution for NEET Practice Test - 6 - Question 13
Dimensions of surface tension

Surface tension = = [MT–2]

Dimensions of tension = [MLT–2]

Hence, dimensions of surface tension and tension are not similar.

While dimensions of stress and pressure are [ML–1T–2]

Planck's constant and angular momentum have dimensions: [ML2T–1].

Also, angle and strain are dimensionless quantities.

NEET Practice Test - 6 - Question 14

A body is released from the top of the tower H metre high. It takes t seconds to reach the ground. Where is the body after t/2 seconds of release?

Detailed Solution for NEET Practice Test - 6 - Question 14
Since the body is released from rest, initial velocity u = 0.

From equation of motion, we have

Displacement of body at time t/2 from the top,

Hence, height of body from the ground =

NEET Practice Test - 6 - Question 15

A bomb of mass 3.0 kg explodes in air into two pieces of masses 2.0 kg and 1.0 kg. The smaller mass goes at a speed of 80 m/s. The total energy imparted to the two fragments is

Detailed Solution for NEET Practice Test - 6 - Question 15
rom law of conservation of momentum, when no external force acts upon a system of two (or more) bodies, the total momentum of the system remains constant.

Momentum before explosion = Momentum after explosion

Since bomb is at rest, its velocity is zero.

Hence,

mv = m1v1 + m2v2

3 x 0 = 2v1 + 1 x 80

v1 = –80 / 2 = –40 m/s

(Since velocity of the second piece is negative, it indicates that the piece is moving in opposite direction to the direction of the other piece.)

Total energy imparted,

KE = 1600 + 3200 = 4800 J

KE = 4.8 kJ

NEET Practice Test - 6 - Question 16

A solid sphere of radius R is uniformly charged with charge density p in its volume. A spherical ft cavity of radius R/2 is made in the sphere as shown. Then electric potential at the centre of sphere will be

Detailed Solution for NEET Practice Test - 6 - Question 16

V = Vsphere at centre - Vcavity

=

NEET Practice Test - 6 - Question 17

Three short dipoles each of dipole moment of magnitude p are placed on a circle of radius R as shown. The magnitude of electric field intensity at centre will be

Detailed Solution for NEET Practice Test - 6 - Question 17
IE1| = |E2| = |E3| = E

NEET Practice Test - 6 - Question 18

Equipotential surfaces corresponding to electric field due to infinite charged sheet are

Detailed Solution for NEET Practice Test - 6 - Question 18
Equipotential surface due uniformly charged plane sheet corresponding to its electric field will be planar.
NEET Practice Test - 6 - Question 19

A galvanometer has a resistance 100 Ω. It gives full scale deflection on passing 10 mA current through it. To convert it into a voltmeter of range 0 - 10 V, the resistance to be added in series is

Detailed Solution for NEET Practice Test - 6 - Question 19

= 900Ω

NEET Practice Test - 6 - Question 20

A charged particle q is shot from a large distance with speed v towards a fixed charged particle Q. It approaches Q upto a closest distance r and then returns. If velocity of q is halved, then the closest distance of approach would be

Detailed Solution for NEET Practice Test - 6 - Question 20
Conservation of energy

R1 = 4 r

NEET Practice Test - 6 - Question 21

Select the correct option

Detailed Solution for NEET Practice Test - 6 - Question 21
Electric potential energy of system of charge depend upon the charge and separation between the charges.
NEET Practice Test - 6 - Question 22

A particle having charge -q and mass m is released from rest on the axis of a fixed ring of total charge Q and radius R from a distance √3 R. Its kinetic energy when it reaches the centre of ring is

Detailed Solution for NEET Practice Test - 6 - Question 22

NEET Practice Test - 6 - Question 23

In the network shown points A, B and C have potential of 70 V, zero and 10V respectively.

The ratio of current in the section AD, DB and DC are

Detailed Solution for NEET Practice Test - 6 - Question 23
i1 + i2 + i3 = 0

VD = 40

NEET Practice Test - 6 - Question 24

Find the current through 10 Q resistor shown in figure

Detailed Solution for NEET Practice Test - 6 - Question 24

Applying KVL in Loop 1,

Applying KVL in Loop 2,

- 3i - 6 ( i - i1) + 4 .5 = 0 ... (ii)

On solving (i) & (ii), i1 = 0

NEET Practice Test - 6 - Question 25

The reading of voltmeter in the figure shown is

Detailed Solution for NEET Practice Test - 6 - Question 25

Req = 500 Ω

NEET Practice Test - 6 - Question 26

In a region of space, suppose there exists a electric field . The potential difference VA - Vo is (where VQ is the potential at the origin and VA the potential at x = 2 m is

Detailed Solution for NEET Practice Test - 6 - Question 26

VA - Vo = -160 V

NEET Practice Test - 6 - Question 27

In the experiment of the meter bridge if length corresponding to null deflection is x, what would be its value if the radius of meter bridge wire is doubled?

Detailed Solution for NEET Practice Test - 6 - Question 27

It is independent on area of metre bridge wire.

NEET Practice Test - 6 - Question 28

In the potentiometer circuit shown in figure, the internal resistance of the 12 V battery is 1Ω and length of the wire AB is 100 cm. When CB is 60 cm, the galvanometer show no deflection. The emf of cell E is (the resistance of wire AB is 3 Ω)

Detailed Solution for NEET Practice Test - 6 - Question 28

NEET Practice Test - 6 - Question 29

A cell of emf E and internal resistance r is connected in series with an external resistance nr. The ratio of the terminal potential difference to emf is

Detailed Solution for NEET Practice Test - 6 - Question 29

E - i(r) = Terminal voltage

= Terminal voltage

NEET Practice Test - 6 - Question 30

A total charge of 20 μC is divided into two parts placed at some distance apart. If the charges experience maximum coulombian repulsion, then the charges should be

Detailed Solution for NEET Practice Test - 6 - Question 30

For maximum force

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