An immersion heater of 400 watts kept on for 5 hours will consume electrical power of 2 kWh.
Resistance of an ideal insulator is infinite.
Reciprocal of resistivity is called conductivity.
Circuit which gives continuously varying potential is called potential divider.
The bulb with the thickest filament among 60W, 100W, and 200W is 200W.
Specific resistance of a wire will depend on the type of material of the wire.
In the given figure, the terminal potential is 12V.
The best material for making bulb filaments is tungsten.
If 1 ampere current flows through a 2m long conductor, the charge flow through it in 1 hour will be 7200C.
A resistance is introduced in a circuit in series deliberately to control current.
All electrical appliances are connected in parallel to each other between the main line and neutral wire to get the same current and potential difference.
Resistance of a conductor depends upon nature of conductor, dimension of conductor, and physical state of the conductor.
When a wire of uniform area of cross-section A, length L, and resistance R is cut into two parts, the resistivity of each part remains the same.
When the same current passes for the same time through a thick and thin wire, more heat is produced in the thin wire.
One kilowatt hour is the amount of energy delivered during one hour.
Resistance of a superconductor is zero.
The best material for making connecting wires is copper.
Internal resistance is the resistance offered by the source of EMF.
Among three bulbs rated at 40W, 60W, and 100W connected in series across 220V mains, all will burn equally brightly.
A 40W bulb generates 144000J of heat in one hour.
Resistance of a wire on increasing its temperature will increase with the rise in temperature.
An electric iron marked 20 volts 500W will consume 24 kWh of units in using it for 24 hours.
In liquids and gases, the current is due to both negative and positive charges.
The graphical representation of Ohm’s law is a straight line.
The resistance of a conductor at absolute zero (0K) is zero almost.
Electrical energy is measured in kilowatt hour.
Electrical energy is converted to heat at the rate of I^2Rt.
A fuse is placed in series with the circuit to protect against high current.
Among 100W, 200W, 300W, and 60W bulbs, the 60W bulb has the least resistance.
Optical active crystals rotate the plane of vibrating light.
In a double-slit experiment, we observe both interference and diffraction fringes.
The property of light that does not change with the nature of the medium is frequency.
The photoelectric effect was given by Einstein.
Longitudinal waves do not exhibit polarization.
A point source of light placed in a homogeneous medium gives rise to a spherical wave front.
Nearly monochromatic light is light from a sodium lamp.
When the crest of one wave falls over the trough of the other wave, this phenomenon is known as destructive interference.
In Young’s double-slit experiment, if white light is used, coloured fringes will be seen.
In an interference pattern, dark fringes are wider than bright fringes.
The blue colour of the sky is due to scattering.
When one mirror of a Michelson Interferometer is moved a distance of 0.5 mm, we observe 2000 fringes, and the wavelength of light used is 5000 Å.
Wavelength of X-rays falling at a glancing angle of 30° on a crystal with atomic spacing 2 x 10^-10 for the first-order diffraction is 4 x 10^-10 m.
In plane polarized light, vibrations take place in a direction perpendicular to the direction of propagation of light.
X-rays cannot be polarized.
In monochromatic red light, a blue book will probably appear to be black.
In the double-slit experiment, if one of the two slits is covered, no interference fringes are observed.
In the shadow of a ball, the central portion appears bright due to diffraction.
Crystals of a material can behave as a diffraction grating.
Sodium chlorate is not optically active.
When light is incident normally on a thin film, the path difference depends upon both the thickness of the film and the wavelength.
The velocity of light was determined accurately by Michelson.
The appearance of colour in thin films is due to interference.
A light ray traveling from a rarer to a denser medium suffers a phase change of 180°.
Diffraction effects are more pronounced for a sharp edge.
A diffraction grating with 500 lines per mm has a slit spacing or grating element equal to 2 x 10^-3 mm.
Light reaches the Earth from the sun in approximately 8 minutes.
According to Einstein, light travels in the form of photons.
The central spot of Newton’s rings is dark.
The locus of all points in a medium having the same phase of vibration is called a wavefront.
Two sources of light are coherent if they emit rays of the same wavelength with a constant phase difference.
Diffraction experiment shows that the wavelength of light is smaller than that of sound.
When a force is parallel to the direction of motion of the body, then the work done on the body is zero.
If a body with a mass of 2 kg is raised vertically through 2m, then the work done will be 78.4 J.
The average power and instantaneous power become equal if work is done at a uniform rate.
Among proton, electron, neutron, and alpha particle with the same momentum, the alpha particle has the highest kinetic energy.
Work done by a variable force is determined by dividing force into small intervals.
Light passing through a Polaroid becomes plane polarized.
Diffraction fringes have a distance between them that increases as the distance from the source increases.
A luminous object emits its own light.
The definition of the meter in terms of the wavelength of red cadmium light was given by Michelson.
The consumption of energy by a 60W bulb in 2 seconds is 120 J.
The escape velocity from Earth’s surface is 11.1 km/s.
If the moon’s radius is 1600 km and g on its surface is 1.6 m/s², the escape velocity on the moon is 2.26 km/s.
When an arrow is released from its bow, its energy is transformed from elastic potential energy to kinetic energy.
The work done by friction is always negative.
The escape velocity of a body in Earth’s gravitational field is independent of its mass.
The source of geothermal energy is the decay of radioactive elements in the Earth.
Work done by the force of friction is always negative.
When the speed of a moving body is doubled, its momentum increases 2 times and kinetic energy increases 4 times.
Frictional force is not a conservative force.
On a clear day at noon, the solar energy reaching the Earth is about 1 kW/m².
Work done will be maximum if the angle between the force F and displacement d is 0°.
A field in which the work done in moving a body along a closed path is zero is called a conservative field.
Frictional force can do no work on the particle on which it acts.
An elevator weighing 3.5 x 10^-6 N is raised to a height of 1000 m, and the work done is 3.5 J.
The relation between horsepower and watt is 1 hp = 746 watts.
The slope of a work-time graph is equal to power.
The dimension of power is [ML²T⁻³].
The dot product of force and velocity is power.
The source of tidal energy is both the sun and the moon.
One megawatt-hour is equal to 3.6 x 10⁶ J.
Work has the same dimension as that of torque.
The relation between the escape velocity V_esc and orbital speed V_o is given by V_esc = √2 V_o.
When two protons are brought together, potential energy between them decreases.
A man lifts vertically a weight of 40 kg through 1 m in 10 s, while a child lifts vertically a weight of 10 kg through a distance of 1 m in 1 s. The child does more work than the man.
Work done on a body equals the change in both its kinetic energy and potential energy.
The tides raise the water in the sea roughly twice in a day.
The highest value of escape velocity in the solar system is for Jupiter.
Gravitational potential energy of a body has no general formula.
When the speed of a moving body is doubled, its kinetic energy is quadrupled.
