Total charge in coulomb of 75.0 kg of electrons

- a)-13.1868 × 10
^{–19}C - b)-8.242 × 10
^{30}C - c)-11.1896 × 10
^{30}C - d)-13.1868 × 10
^{12}*C*

Correct answer is option 'D'. Can you explain this answer?

Madan Jana answered • yesterday

Weight of electron is 9.11Ã—10^(-31)kg.

Let electron number is N in 75kg

then N=75kg/(9.11Ã—10^(-31)kg).

Then charge of 75kg electron is (NÃ—1.6Ã—10^(-19))

Where charge of one electron is 1.6Ã—10^(-19)

Let electron number is N in 75kg

then N=75kg/(9.11Ã—10^(-31)kg).

Then charge of 75kg electron is (NÃ—1.6Ã—10^(-19))

Where charge of one electron is 1.6Ã—10^(-19)

Light refracts when it goes from air to water, this is because which of the following get smaller?

- a)wavelength, speed
- b)wavelength, frequency
- c)speed, frequency
- d)all three

Correct answer is option 'A'. Can you explain this answer?

Pie Academy answered • 3 days ago

When **light travels from air** into **water**, it slows down, causing it to change direction slightly. This change of direction **is** called refraction. When **light** enters a more dense substance (higher refractive index), it 'bends' more towards the normal line.

Yikker Yikker asked • 5 hours ago

A pendulum is made of a massless string of length L and a small bob of negligible size and mass m. It is released making an angle q0 (<<1 rad) from the vertical. When passing through the vertical, the string slips a bit from the pivot so that its length increases by a small amount d(d << L) in negligible time. If it swings up to angle q1 one the other side before starting to swing back, then to a good approximation which of the following expressions is correct?

Deepak Singh asked • 5 hours ago

The variation of binding energy per nucleon with respect to the mass number of nuclei is shown in the figure.

Consider the following reactions:

- a)Both (1) and (2) are allowed
- b)Both (1) and (2) are forbidden
- c)(1) is forbidden and (2) is allowed
- d)(1) is allowed and (2) is forbidden

Correct answer is option 'C'. Can you explain this answer?

PARUL PATEL asked • 7 hours ago

A disk of radius q/4 having a uniformly distributed charge 6C is placed in the x-y plane with its centre at A rod of length a carrying a uniformly distributed charge 8C is placed on the x-axis from Two point charges - 7C and 3C are placed at respectively. Consider a cubical surface formed by six surfaces The electric flux through this cubical surface is

- a)-2C/ε
_{0} - b)2C/ε
_{0} - c)10C/ε
_{0} - d)12C/ε
_{0}

Correct answer is option 'A'. Can you explain this answer?

RAJNEESH SHARMA asked • 7 hours ago

An infinitely long hollow cylinder of radius R carrying a surface charge density σ is rotated about its cylindrical axis with a constant angular speed ω. The magnitude of the surface current is

- a)2σRω
- b)σR
^{2}ω - c)2πσRω
- d)πσRω

Correct answer is option 'B'. Can you explain this answer?

Sumoksha Parhi asked • 9 hours ago

A ball impinges directly on a similar ball at rest. The first ball is brought to rest by the impact. If half the kinetic energy is lost by impact. What is the value of the coefficient of restitution?

- a)1/2√2
- b)√3/2
- c)1/√2
- d)1/√3

Correct answer is option 'C'. Can you explain this answer?

Vikram Bhatia asked • 10 hours ago

Which of the following mapping is not linear ?

- a)F : R
^{2}→ R^{2}; F(x, y) = (x + y, x) - b)F : R
^{2}→ R^{3}; F(x, y) = (x + 3, 2y, x + y) - c)F : R
^{3}→ R^{3}; F(x, y, z) = (x + 2y – z, y + z, x + y – 2z) - d)F : R
^{2}→ R^{2}; F(x, y) = (x – y, x – 2y)

Correct answer is option 'B'. Can you explain this answer?

Arka Bhattacharjee asked • 10 hours ago

A fire alarm sounds with a frequency of 480 Hz. Two fire engines dash to the site to extinguish the fire from opposite directions. One travels with a speed of 33 m/s and the other with 27m/s. If the velocity of sound in air be 330 m/s, the difference between the frequencies of the sirens are heard by the drivers of the two fire engines will be :

- a)4 Hz
- b)12 Hz
- c)8 Hz
- d)24 Hz

Correct answer is option 'C'. Can you explain this answer?

Shraddha Wadighare asked • 10 hours ago

Let X be a random variable of continuous type with probability density function f(x). Then, based on single observation X, the most powerful test of size α = 0.1 for testing H_{0} : f(X) = 2x, 0 < x < 1, against H_{1} : f(X) = 4x^{2}, 0 < x < 1, has power

- a)9/10
- b)1/10
- c)81/100
- d)19/100

Correct answer is option 'D'. Can you explain this answer?

Pradeep Pal asked • 10 hours ago

A mass m, lying on a horizontal, frictionless surface, is connected to one end of a spring. The other end of the spring is connected to a wall, as shown in the figure. At t = 0, the mass is given an impulse.

The time dependence of the displacement and the velocity of the mass (in terms of non- zero constants A and B) are given by

Pallavi Khotele asked • 10 hours ago

A system consists of N number of particles, N » 1. Each particle can have only one of the two energies E1 or E1 + ε (ε > 0). If the system is in equilibrium at a temperature T, the average number of particles with energy E_{1} is

- a)
- b)
- c)
- d)

Correct answer is option 'C'. Can you explain this answer?

Bibhuti B. Behera asked • 12 hours ago

Two particles A and B of mass m and one particle C of mass are kept on the x axis in thr order ABC, Particle A is given a velocity vi . Consequently there are two collisions, both of which are completely inelastic. If the net energy loss because of these collisions is 7/8 of the initial energy,, the value of M is (ignore frictional losses)

- a)8 m
- b)6 m
- c)4 m
- d)2 m

Correct answer is option 'B'. Can you explain this answer?

Narendra Nari asked • 13 hours ago

A system consisting of n components functions if, and only if, at least one of n components functions. Suppose that all the n components of the system function independently, each with probability 3/4. If the probability of functioning of the system is 63/64, then the value of n is

- a)2
- b)4
- c)3
- d)5

Correct answer is option 'C'. Can you explain this answer?

Suruchi Somwanshi asked • 14 hours ago

A die is thrown (n + 2) times. After each throw a ‘+’ is recorded for 4, 5 or 6 and ‘–’ for 1, 2 or 3, the signs forming an ordered sequence each, except the first and the last sign, is attached a characteristic random variable which takes the value 1 if both the neighbouring signs differ from the one between them and 0 otherwise. If X_{1}, X_{2}, ..., X_{n} are characteristic random variables, find the mean and variance of

Shivani Sharma asked • 16 hours ago

Consider the function f (x, y) = x^{3} − 3xy^{2}, x,y ∈ ℝ. Which one of the following statements is TRUE?

- a)f has a local minimum at (0, 0)
- b)f has a local maximum at (0, 0)
- c)f has global maximum at (0, 0)
- d)f has a saddle point at (0, 0)

Correct answer is option 'D'. Can you explain this answer?

Aditi Choudhury asked • 18 hours ago

Let S be the surface in R^{3} defined by the parametric equation

r = 2 + cos t + cos u

θ = t 0 ≤ t ≤ 2π

z = sin u 0 ≤ u ≤ 2π

then the using the divergence theorem what is the volume of the region inside S.

- a)4π
^{2} - b)-4π
^{2} - c)4π
- d)-4π

Correct answer is option 'A'. Can you explain this answer?

Vrushabh Kshirsagar asked • yesterday

Let 0 < a < 1 and let <xn> satisfy the condition |x_{n+1} – x_{n}| ≤ a_{n} for n ∈ N then which of the following statements are TRUE ?

- a)<x
_{n}> is convergent - b)<x
_{n}> is cauchy - c)<x
_{n}> is bounded - d)<x
_{n}> is not cauchy

Correct answer is option 'A,B,C'. Can you explain this answer?

Ramanuj Pandey asked • yesterday

Consider two identical, finite, isolated systems of constant heat capacity C at temperatures T_{1} and T_{2}, (T_{1} > T_{2}). An engine works between them until their temperatures become equal. Taking into account that the work performed by the engine will be maximum (=W_{max}) if the process is reversible (equivalently, the entropy change of the entire system is zero), the value of W max is:

- a)C(T
_{1}– T_{2}) - b)C(T
_{1}– T_{2})/2 - c)C(T
_{1}+ T_{2}- √T_{1}T_{2}) - d)C(√ T
_{1}-√ T_{2})2

Correct answer is option 'D'. Can you explain this answer?

The Black Planet. asked • yesterday

Consider a free electron (e) and a photon (ph) both having 10 eV of energy. If λ and P represent wavelength and momentum respectively, then

(mass of electron = 9.1 x 10^{-31} kg; speed of light = 3 x 10^{8} m/s)

(mass of electron = 9.1 x 10

- a)λ
_{e}= λ_{pℎ}and P_{e}= P_{pℎ}. - b)λ
_{e}< λ_{pℎ}and P_{e}> P_{pℎ}. - c)λ
_{e}> λ_{pℎ}and P_{e}< P_{pℎ}. - d)λ
_{e}< λ_{pℎ}and P_{e}< P_{pℎ}.

Correct answer is option 'B'. Can you explain this answer?

Unni Vinod asked • yesterday

The dispersion relation for electromagnetic waves travelling in a plasma is given as w^{2} = c^{2}k^{2} + w_{p}^{2}, where c and w_{p} are constants. In this plasma, the group velocity is :

- a)proportional to but not equal to the phase velocity
- b)inversely proportional to the phase velocity
- c)equal to the phase velocity
- d)a constant

Correct answer is option 'B'. Can you explain this answer?

Bikash Kumar Roy asked • yesterday

In an electron microscope, electrons are accelerated through a potential difference of 200kV. What is the best possible resolution of the microscope?

(Specify your answer to two digits after the decimal point.)

Correct answer is between '2.30,3.20'. Can you explain this answer?

Sanskriti Rastogi asked • yesterday

Consider a system of N particles obeying classical statistics, each of which can have an energy 0 or E. The system is in thermal contact with a reservoir maintained at a temperature T. Let k denote the Boltzmann constant. Which one of the following statements regarding the total energy U and the heat capacity C of the system is correct ?

- a)
- b)
- c)
- d)

Correct answer is option 'C'. Can you explain this answer?

VEENA MODANI asked • yesterday

The depletion layers in a **p-n** junction diode consists of layers of :

- a)Negatively charged on the p-side and positively charged acceptors on the n- side
- b)Positively charged donors on the p-side and negatively charged acceptors on the /7-side
- c)Positively charged donors on the n-side and negatively charged acceptors on the p-side
- d)Negatively charged donors on the n-side and positively charged acceptors on the p-side

Correct answer is option 'C'. Can you explain this answer?

RASHMI NAGPAL asked • yesterday

The fermi level of an intrinsic semi-conductor is pinned at the centre of the band-gap. The probability of occupation of the highest electronic state in valence band at room temperature, will b e :

- a)between zero and half
- b)one
- c)half
- d)zero

Correct answer is option 'C'. Can you explain this answer?

SHEELU AGRAWAL asked • yesterday

The electrical conductivity of a semi-conductor in cases when electromagnetic radiation of wave length shorter than 2480 nm is incident on it. What is the band - gap Mark -0 .33 out of 1.00 (in eV) for the semiconductor?

(take h = 6.67 x10^{-34} J-s).

(take h = 6.67 x10

- a)0.5
- b)0.9
- c)0.7
- d)1.1

Correct answer is option 'A'. Can you explain this answer?

Shraddha Wadighare asked • yesterday

In a colony all families have at least one child. The probability that a randomly chosen family from this colony has exactly k children is (0.5)^{k} ; k = 1, 2,K . A child is either a male or a female with equal probability. The probability that such a family consists of at least one male child and at least one female child is _________

Correct answer is '0.3 to 0.4'. Can you explain this answer?

Deepak Sethi asked • yesterday

A train passes through a station with a constant speed. A stationary observer at the station platformmeasures the tone of the train whistle as 484 Hz when it approaches the station and 442 Hz when itleaves the station. If the sound velocity in air is 330 m/s, then the tone of the whistle and the speedof the train are

- a)462 Hz, 54 km/h.
- b)463 Hz, 52 km/h.
- c)463 Hz, 56 km/h.
- d)464 Hz, 52 km/h.

Correct answer is option 'A'. Can you explain this answer?

Dheeraj Bhakat asked • 2 days ago

For an n- p- n transistor connected as shown in the figure. V_{BE} = 0.7V. Given that reverse saturation current of the junction at room temperature 300^{o} k is 10^{-13} A, the emitter current is ______

- a)
- b)
- c)
- d)

Correct answer is option 'A'. Can you explain this answer?

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A ring of mass **m** can slide over a smooth vertical rod. The ring is connected to a spring of force constant *k* = **4***mg*/*R* where **2***R* is the natural length of the spring. The other end of the spring is fixed to the ground at a horizontal distance **2***R * from the base of the rod. The mass is released at a height of **1.5***R* from the ground.

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A particle is moving in space with O as the origin. Some possible expressions for its position velocity and acceleration in cylindrical coordinate (p,φ,z) are given below, which of the following are correct?

- a)Position vector
- b)velocity vector
- c)accleration vector
- d)accleration vector

Correct answer is option 'A,B,D'. Can you explain this answer?

Jagadeesh Pidugu asked • 2 days ago

The total energy of an ionic solid is given by where a is the Madelung constant, r is the distance between the nearest neighbour in the crystal. If r0 is the equilibrium separation then the constant B is given by ______

- a)
- b)
- c)
- d)

Correct answer is option 'A'. Can you explain this answer?

Sanjid Km Sanju asked • 3 days ago

A person is standing in an elevator. The situation in which he finds his weight less than actual is when

- a)The elevator moves upward with uniform velocity
- b)The elevator moves downward with constant acceleration
- c)The elevator moves downward with uniform velocity
- d)The elevator moves upward with constant acceleration

Correct answer is option 'B'. Can you explain this answer?

Biki 2000 asked • 3 days ago

Two particles of mass **m** each are tied at the ends of a light string of length **2***a. *The whole system is kept on a frictionless horizontal surface with the string held light so that each mass is at a distance **a** from the centre *P* (as shown in the figure). Now, the mid point of the string is pulled vertically upwards with a small but constant force *F*. As a result, the particles move towards each other on the surface. The magnitude of acceleration, when the separation between them becomes **2****x**, is :

Abhas Khandelwal asked • 3 days ago

Two blocks *A* and *B* of masses *m* and **2***m* respectively are held at rest such that the spring is in natural length. Find out the accelerations of blocks *A* and *B* respectively just after release (pulley, string and the spring are massless).

- a)0, 0
- b)
- c)
- d)

Correct answer is option 'C'. Can you explain this answer?

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