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### What should be the velocity(v) of a sound source moving towards a stationary observer

What should be the velocity(v) of a sound source moving towards a stationary observer so that apparent frequency is double the actual frequency

Options

(a) v (b) 2v (c) v/2 (d) v/4

Correct […]

### A liquid boils when its vapour pressure equals

A liquid boils when its vapour pressure equals

Options

(a) The atmospheric pressure (b) Pressure of 76.0 cm column of mercury (c) The critical pressure (d) The dew point of the surroundings

Correct […]

### Two point charge +9e and +e are at 16 cm away from each other.

Two point charge +9e and +e are at 16 cm away from each other. Where should another charge q be placed between them so that the system remains in equilibrium?

Options

(a) 24 […]

### The threshold wavelength for photoelectric effect of a metal is 6500 Å. The work function

The threshold wavelength for photoelectric effect of a metal is 6500 Å. The work function of the metal is approximately

Options

(a) 0.1 eV (b) 1 eV (c) 2 eV (d) 3 eV

### The temperature coefficient of a resistance wire is 0.00125 per degree.

The temperature coefficient of a resistance wire is 0.00125 per degree. The resistance at 300 K is 1 Ω. At what temperature its resistance will be 2Ω?

Options

(a) 1154 K (b) 1127 K […]

### The order of radius of the nucleus of an atom is

The order of radius of the nucleus of an atom is

Options

(a) 10⁻¹⁰ m (b) 10⁻¹² m (c) 10⁻¹⁵ m (d) 10⁻¹⁷ m

10⁻¹⁵ m

Explanation:

No explanation available. Be […]

### The radius of the first orbit of the hydrogen atom is a₀. The radius of the second orbit

The radius of the first orbit of the hydrogen atom is a₀. The radius of the second orbit will be

Options

(a) 4 a₀ (b) 6 a₀ (c) 8 a₀ (d) 10 a₀

### The voltage of an a.c.supply varies with time (t) as V=120 sin 100 πt the maximum voltage

The voltage of an a.c.supply varies with time (t) as V=120 sin 100 πt cos 100 πt the maximum voltage and frequency are respectively

Options

(a) 120 V and 100 Hz (b) 120√2 v […]

### Periodic time of a satellite revolving above Earth’s surface at a height equal to R,

Periodic time of a satellite revolving above Earth’s surface at a height equal to R, radius of Earth is (g=acceleration due to gravity at Earth’s surface)

Options

(a) 2π√2R/g (b) 4√2√R/g (c) 2π√R/g […]

### A particle doing SHM has amplitude=4 cm and time period = 12 sec. The ratio between times

A particle doing SHM has amplitude=4 cm and time period = 12 sec. The ratio between times taken by it in going from its mean position to 2 cm and from 2 cm to extreme […]

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