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(1) Thinner wire will have more resistance because the resistance is inversely proportional to the area of cross-section.

(2) Specific resistance of both wire is same because specific resistance depends on the nature of the material which is same in both cases.

An ohmic resistor is a resistor which obeys ohm's law. Examples are all metallic conductors such as silver, aluminium, copper, etc.

(i) As the bucket is filled, the sound becomes shriller due to decrease in length of air column and increase in frequency. 

(ii) The change in sound takes place due to change in frequency of sound due to decrease in the length of the air column.

The SOUND BECOMES SHRILLER AND SHRILLER as the water in the bucket rises, the length of air column decreases. So the frequency of the sound produced INCREASES. Thus by hearing the sound from a distance, one can get the idea of water level in the bucket

 (i) X-rays. 

(ii) Speed of the wave in vacuum is 3 x 10⁸ m/s.

(iii) x-rays are used for determining fracture of bones hidden objects in customs at Airports.

Ultrasonic waves.

Scattering of light is the process of absorption and then re-emission of light energy in many different directions.

The colour of white light which scattered the least is red. This is because red colour has the longest wavelength 8000 Å and lowest frequency 3.75 x 10¹⁴ Hz.

The ultrasonic waves are used because they can travel undeviated through a long distance.

(i) X-Ray. 

(ii) 3 x 108 m/s. 

(iii) X-Ray are used for detection fracture in bones.

(i) X-rays. 

(ii) X-rays are used for detection of fracture in bones, teeth etc.

(i) Turning effect of force acting on a body about an axis is called moment of force. It is equal to the product of magnitude of force and the perpendicular distance of the line of action of force from the axis of rotation.

(ii) Clockwise.

Moment of force : It is equal to the product of the magnitude of the force and the perpendicular distance of the line of action of force from the axis of rotation.

(i) Turning effect of force acting on a body about an axis is called moment of force. It is equal to the product of magnitude of force and the perpendicular distance of the line of action of force from the axis of rotation. 

(ii) Clockwise.

 If moment of force is assigned a negative value, it means clockwise tendency of force.

(i) Compressed spring : It has potential energy. 

(ii) Potential energy of the spring is imparted to the ball in the form of kinetic energy.

(i) Refractive Index : It is defined as the ratio of velocity of light in medium 1 to the velocity of light in medium 2. 

(ii) Ray 2 shows partially reflected ray.

(i) Potential Energy 

(ii) Since P.E. is converted into K.E which transferred to the ball and makes the ball flyaway.

(i) Solar energy to Electrical energy. 

(ii) Solar cell is not a constant source of energy.

First we place the lens on a piece of printed paper. Then we lift it slowly. If the words of the printed paper, seen through the lens becomes bigger or magnified then it is convex lens otherwise concave lens.

On moving the printed piece of paper before the lens, if the image is always diminished then it is a concave lens otherwise it is a convex lens.

Dispersion of light : When a beam of white light falls on a prism it splits into the rays of constituent colours. This is known as dispersion of light.

These waves are not audible to us because their frequency lies beyond the limits of audibility (20 Hz - 20,000 Hz).

The ultrasonic waves are not audible to us because they have frequency more than 20,000 Hz.

(i) Isobars nucleus) 

(ii) When the number of neutrons is much more than the number of protons in the nucleus of an atom, under such condition it tends to be radioactive.

In a beam balance when the beam is balanced in a horizontal position, it is in Static equilibrium.

(i) Work done is given by the product of the force (F) and the displacement (d) in the direction of the force 

i.e., Work done = F x d

(ii) Work done is measured by the product of the force (F) and the component of displacement (d) in the direction of the force

i.e., Work done = F x d cos θ

Where θ is the angle which the displacement makes with the direction of the force.

(i) Force 

(ii) 1 K Wh = 3.6 x 10⁶ J

(i) Chemical energy to the light and heat energy. 

(ii) Heat energy to mechanical energy.

Energy changes : 

(i) Burning of a candle: Chemical energy to light energy. 

(ii) Steam engine: Chemical energy of coal first changes to heat energy of steam and then heat energy charges into mechanical energy.

(i) The resistivity of semiconductors decreases with increase in temperature.

(ii) Thicker

(i) X-rays 

(ii) They are used for the detection of fracture in bones.

(i) The resistivity of semiconductor decreases with the increase in temperature. 

(ii) Thicke

Water boils at higher temperature because of the increase in pressure or the presence of some impurity. More the impurity or pressure, more will be the boiling point.

Water might have some impurities (eg., salt) dissolved in it. Because the boiling point of liquid (water) increases by the addition of impurities (eg., salt) to it.

(i) Current carrying freely suspended solenoid behaves just like a bar magnet with fixed polarities (North and South) at its ends. Hence it rest in North- South direction exactly in the same manner as a bar magnet does. 

(ii) North-South direction.

(i) Work done by a force when the force is in the direction of displacement = Force × Displacement of the point of application of the force in the direction of force. 

(ii) Work done by a force when the force is at an angle [θ] to the direction of displacement = Force × component of displacement in the direction of force = Force × d cos θ 

[d is the displacement of the body at the angle θ to the direction of force]

(i) When a number of forces acting on a body produce no change in its state of rest or of the motion, the body is said to be in equilibrium. 

(ii) Static equilibrium.

The factors affecting turning effect of a body: 

1. The magnitude of a force applied. 

2. The distance of line of action of the force from the axis of rotation.

The perpendicular distance of the line of action of force from the axis rotation.

On reversing the direction of the current in a wire,the magnetic field produced by it gets Reversed.

The position of the centre of gravity of a body depends on its shape , i 'e., the distribution of mass in it.

The thickness of glass slab affects the lateral displacement of light as it passes through a rectangular glass slab.

(i) The position of centre of gravity of a body of given mass depends on its shape i.e., on the distribution of mass in it. 

(ii) S.I. unit of the moment of force is Newton × meter.

(i) The factors that affect the lateral displacement of a light as it passes through a rectangular glass slab are : 

(1) The thickness of the glass slab: The lateral displacement increases with the increase in the thickness of the glass slab. 

(2) The angle of incidence: It increases with the increase in the angle of incidence. 

(3) The refractive index of glass: The wavelength of light used. (It is more for violet light than for the red light.) (any one) 

(ii) ‘Reversed’.

(i) The function of anode in a cathode ray tube is to accelerate the electrons and also focus them in a fine energetic beam. 

(ii) In a cathode ray tube electrical energy is converted into light energy. 

(iii) To check the waveform of varying electrical signals.

(i) Normal reaction force. 

(ii) It acts normal to the Surface of table top i.e., opposite to the direction of the force due to the weight of the body.

(i) ^A_ZX → ^A _Z+1 Y + ⁰ _-1  β  

(ii) Isobars. 

(iii) Isotopes of all elements of atomic number higher than 82 and elements having number of neutrons exceeding the number of protons in their nuclei are tend to be radioactive.

The sound heard after reflection from a distant obstacle (cliff, wall etc.) after the original sound has ceased, is called an echo. 

 Specific heat capacity of A is 3.8 tg^-1 K^-1.

Specific heat capacity of B is 0.4 Jg^-1 K^-1.

(i) 'B' is a good conductor of heat. 

(ii) The specific heat capacity of B is lower than A. this means that less heat is required to raise the temperature of 1g B by 1K than the heat required to A.

(iii) 'A' Will be preferred as it absorbs large amount of heat energy without raising its own temperature much as its specific heat capacity is high.

(i) In set A, bulbs are in series so if one gets fused, others are also affected. In set B, bulbs are in parallel so if one goes off, others continue to glow.

(ii) For house circuiting, we use the set B arrangement i.e., all the appliances are connected in parallel because in this arrangement each appliance operates at the same voltage and works independently without being affected whether the other appliance is switched on or off.