Current Electricity - MCQs

Current Electricity - MCQs Points : Current Electricity, mcqs, Current Electricity fill in the blanks, mechanics objective type questions 1. The specific resistance of all metals is most affected by
(a) applied magnetic field
(b) illumination
(c) pressure
(d) temperature

2. Through a metallic conductor an electric current is passed due to the drift of
(a) protons
(b) neutrons
(c) +ve ions
(d) free electrons

3. Through an electrolyte an electric current is passed due to the drift of
(a) protons
(b) free electrons
(c) + ye and -ye ions
(d) free electrons and holes

Optics - MCQs

Optics - MCQs Points : optics mcqs, optics fill in the blanks, optics objective type questions 1. A lamp is hanging at a height 40 cm from the centre of a table. If its height is increased by 10 cm the illuminance on the table will decrease by
(a) 10%
(b) 20%
(c) 27%
(d) 36%

2. Inverse square law for illuminance is valid for
(a) isotropic point source
(b) acylindrical source
(c) a search light
(d) all types of sources

3. In a movie hail, the distance between the projector and the screen is increased by 1%. The illumination on the screen is
(a) increased by 1%
(b) descreased by 1%
(c) increased by 2%
(d) decreased by 2%

Mechanics - MCQs

Mechanics - MCQs Points : mechanics - mcqs, mechanics fill in the blanks, mechanics objective type questions 1. Plank’s constant has the dimensions of
(a) energy
(b) work
(c) linear momentum
(d) angular momentum

2. The unit of power is
(a) kilowatt
(b) kilowatt-hour
(c) dyne
(d) joule

3. In the S.I. system, the unit of temperature is
(a) degrees centigrade
(b) kelvin
(c) degrees celsius
(d) degrees fahrenheit

Conversion of Electrical Energy to Mechanical Energy

Conversion of Electrical Energy to Mechanical Energy Points : Conversion of Electrical Energy to Mechanical Energy Electromechanical energy conversion means conversion of electrical energy into mechanical energy or mechanical energy into electrical energy.

TYPES OF MOTION

TYPES OF MOTION

Motion can be classified into following three types.

• Translatory motion

• Rotatory motion

• Oscillatory (Vibratory) motion.

1. TRANSLATORY MOTION

Definition: A motion of a body in which every particle of the body is being displaced by the same amount is called translational motion.

EXAMPLES:

• Motion of a car on a straight road.

• Motion of a train.

• Motion of falling bodies.

2. ROTATORY MOTION

Definition: When an object spins or rotates about a fixed point or axis, its motion is called rotational motion. OR Motion confined to a circle is called rotatory motion.

EXAMPLES:

• Rotation of Ferris wheel.

• Rotation of wings of electric fan

• Rotation of electron around nucleus

3. OSCILLATORY (VIBRATORY) MOTION:

Definition: To and fro motion of an object about a mean position executed at regular intervals of time is called vibratory motion.

EXAMPLES:

• Motion of pendulum.

• To and fro motion of a swing.

• Motion of wings of a bird.

Motion

Motion
Definition: When a body changing its position with respect to its surroundings is said to be in a state of Motion.

Example:

• The motion of a moving bus can be detected from its changing position with respect to its surrounding. 
• The motion of a moving train can be detected from its its changing position with respect to its surrounding.

Rest

REST

Definition: When a body is not changing its position with respect to its surrounding is said to be in a state of rest.

Example:

1. A Book lying on a table.

2. A Bus standing on the stop.

3. A bird sitting on a wall.

KINEMATICS

KINEMATICS

Definition: The branch of physics that deals with the description of motion of objects without reference to the force or agents causing motion is called Kinematics.

OR

Kinematics is the study of how things move. Here, we are interested in the motion of normal objects in our world. A normal object is visible, has edges, and has a location that can be expressed with (x, y, z) coordinates. We will not be discussing the motion of atomic particles.

MEASURING CYLINDER

MEASURING CYLINDER:

Definition: It is a device used to measure the volume of liquid.

Construction: It is a glass cylinder with a scale in cubic centimeters or millimeters marked on it.

Working: When a liquid is poured. it rises to a certain height in the cylinder. the level of liquid in cylinder is noted and volume of liquid is obtained.

PHYSICAL BALANCE

PHYSICAL BALANCE:

Definition:  It is a device commonly used to measure the mass of an object.

CONSTRUCTION: It consists of a vertical pillar having a horizontal beam. resting on a center knife edge with two pans, which are suspended on two knife-edges near each end of the beam. A long pointer capable of swinging on a scale is attached to the middle of the beam. The physical balance is leveled by means of leveling screws. The beam is set free by rotating the arresting knob. The pointer is adjusted at the center of the scale by means of adjusting screws.

MICROMETER - SCREW GAUGE

MICROMETER SCREW GAUGE

Definition: It is an instrument used to measure the distance accurately up to 0.01 mm OR 0.001 cm.

Construction:

A micrometer screw gauge consists of a fine screw of usually I or 0.5 mm pitch, which moves when rotated through a nut. Screw gauge also has a linear scale, which is parallel to the axis of the screw and is known as main scale and a circular scale, which is divided into 100 or 50 divisions.

Pitch of Screw Gauge:

Distance between the two consecutive threads of the linear screw is called pitch.

LEAST COUNT OF THE SCREW GAUGE (L.C.):

Definition: Least count is the minimum measurement that can be measured with the help of screw gauge.

Least Count = Pitch of the screw gauge / No. of divisions on the circular scale

VERNIER CALIPER

VERNIER CALIPER

Definition: It is an instrument used to measure the distance accurately up to 0.1 mm

Construction:

It consists of a graduated centimeter bar known as main scale with a moveable scale or 10 divisions known as vernier scale. It has two sets of jaws for the measurement of internal and external diameter of cylindrical objects.

VERNIER CONSTANT (V.C.) OR LEAST COUNT (L.C.):

Definition: Vernier constant or the least count is the minimum measurement that can be measured by vernier calipers.

Formula:

Least Count = 1 main scale division - 1 Vernier scale div.

                    = 1 mm - 0.9 mm

                    = 0.1 mm

                    = 0.1/10

                    = 0.01 Cm

   OR

V.C. = Value of one main scale division / Total number of vernier scale divisions

        = 1/110

        = 0.1 mm

        = 0.01cm

ZERO ERROR:

On closing the jaws if the zero of the main scale does not coincide with the zero of the vernier scale then the instrument has zero error.

POSITIVE ZERO ERROR:

On closing the jaws if the zero of the vernier scale is on the right of the main scale then the zero error is positive.

NEGATIVE ZERO ERROR:

On closing the jaws if the zero of the vernier scale is on the left of the main scale then the zero error is negative.

PASCAL LAW - BRAKE SYSTEM - HYDRAULIC LIFT - HYDRAULIC PRESS

PASCAL’S LAW

Definition: Liquids transmit external pressure equally in all directions, which acts perpendicularly to the walls of container.

THE HYDRAULIC BRAKE SYSTEM

Hydraulic break system used to stop moving vehicles and work on the basis of Pascal’s principle.

Construction:

The hydraulic brake system consists of a master cylinder joined by tubes to four smaller cylinders, one for each wheel of the car. They ate called brake cylinder .All cylinders are provided with oil tight pistons.

Working

A forward push on the brake pedal causes a force on the piston in the master cylinder and a consequent pressure on the brake oil. These undiminished transmitted pressure forces the piston in each brake cylinder to act on the brake shoe attached to a caliper or against a rotor in the case of disk brake. The resulting friction stops the car.

HYDRAULIC LIFT

Construction:

In hydraulic lift a narrow cylinder ‘A' is connected with a wider cylinder 'B' and they are fitted with airtight pistons. Cylinders are filled with some incompressible fluid.

Working

Pressure applied downward on the piston A is transmitted undiminished on each unit area on the piston of cylinder B. The piston B serve as a platform for a car or any heavier object to lift.

HYDRAULIC PRESS

Construction:

In hydraulic press a narrow cylinder 'A' is connected with a wider cylinder 'B' and they are fitted with airtight pistons. The cylinder 'B' is provided with a rigid roof over it. Cylinders are filled with some incompressible fluid.

Working

Pressure applied downward on the piston A is transmitted undiminished on each unit area on the Hydraulic Press piston of cylinder B. The piston B moves upward and compress the material placed between piston 'B' and the roof over it.