General Physics

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346 When a piece of pure silicon is doped with aluminium, then

A
The conductivity of the doped silicon piece will remain the same
B
The doped silicon piece will become n-type
C
The doped silicon piece will become p-type
D
The resistivity of the doped silicon piece will increase

347 When two semiconductors of p and n-type are brought in contact, they form p-n junction which acts like a/an

A
Conductor
B
Oscillator
C
Rectifier
D
Amplifier

348 Why does bleeding occur through the nose in high mountainous regions ?

A
The pressure of blood in capillaries is greater than the outside pressure
B
The pressure at high altitudes is greater than that on the plains
C
The blood pressure of a person increases at high altitudes
D
The blood pressure fluctuates and finally decreases drastically

349 Which of the following pairs of physical quantities have the same dimensions?

A
Force and Power
B
Work and Power
C
Work and Energy
D
Momentum and Power

350 Which of the following is used to split white light into different colours ?

A
Glass slab
B
Convex lens
C
Concave lens
D
Prism

351 Remote-sensing device has an inbuilt source of :

A
X-ray
B
g-ray
C
ultraviolet ray
D
infrared ray

352 A single fixed pulley is used to draw water from a well because

A
efficiency is 100%
B
velocity ratio is low
C
mechanical advantage is high
D
force is applied in a convenient direction

353 A bullet is fired from a rifle which recoils after firing. The ratio of kinetic energy of the rifle to that of the bullet is :

A
zero
B
one
C
less than one
D
more than one

354 A copper disc has a hole. If the disc is heated, the size of the hole

A
increases
B
decreases
C
No change
D
first increases and than decreases

355 Sound waves in air are

A
transverse
B
longitudinal
C
electromagnetic
D
polarised

356 Magnetism at the centre of a bar magnet is :

A
minimum
B
maximum
C
zero
D
minimum or maximum

357 It is more difficult to walk on a sandy road than on a concrete road because

A
sand is soft and concreter is hard.
B
the friction between sand and feet is less than that between concrete and feet.
C
the friction between sand and feet is more than that between concrete and feet.
D
the sand is grainy but concrete is smooth.

358 Find the maximum velocity for the overturn of a car moving on a circular track of radius 100 m. The co-efficient of friction between the road and tyre is 0.2

A
0.14 m/s
B
140 m/s
C
1.4 km/s
D
14 m/s

359 Of the following properties of a wave, the one that is independent of the other is its

A
amplitude
B
velocity
C
wavelength
D
frequency

360 Which one among the following components is used as an amplifying device?

A
Transformer
B
Diode
C
Capacitor
D
Transistor