Robots are automated machines which have many mechanical parts like wheels, arms, fingers, legs etc. Therefore a strong material is needed. For a given size, steel has several times stronger.

The leakage current is the current that the diode will leak when a reverse bias is applied to it.

RADAR stands for RAdio Detection And Ranging.

One curie was defined as number of decays per second in 1 gram of radium. 1 1 curie = 3.7 X 10¹⁰ decays/s.

Isotopes are atoms of the same element having same atomic number Z, but different mass number A.
(Ex: Hydrogen, \(_{ 1 }^{ 1 }{ H }\) ((hydrogen), \(_{ 1 }^{ 2 }{ H }\) (deuterium),and \(_{ 1 }^{ 3 }{ H }\) (tritium)) 

Salient features of corpuscular theory:
(i) A luminous body emits tiny massless perfectly elastic particles called corpuscles.
(ii) As the corpuscles are very small, the source does not suffer appreciable loss of mass.
(iii) They are not affected by gravity. so they travel with high speed in a straight line.
(iv) When these corpuscles impinge on the retina of the eye, the vision is produced.
(v) The different size of corpuscles is the reason for different colors.
(vi) The reflection is due to repulsion of the corpuscles by the medium.
(vii) The refraction is due to the attraction of the corpuscles by the medium.
(viii) This theory could not explain the reason why the speed of light is lesser in denser medium than in denser medium and also the phenomena like interference, diffraction and polarisation.

The angle between the incident ray and deviated ray of light ray is called Angle of deviation due to reflection. d = 180 - 2i

The principle of reversibility states that light will follow exactly the same path if its direction of travel is reversed.

Hysteresis is the phenomenon of lagging of magnetic induction behind the magnetising field.

Coulomb's inverse square law states that the force of attraction or repulsion between two magnetic poles is directly proportional to the product of their pole strengths and inversely proportional to the square of the distance between them.
\(\vec { F } =k \frac { { q }_{ m_{A} }{ q }_{ m_{B} } }{ { r }^{ 2 } } \hat { r } \)

The current in an AC circuit is said to be wattless current if the power consumed by it is zero.

Even for a conductor in the form of a sheet or plate, an emf is induced when magnetic flux linked with it changes. But the difference is that there is no definite loop or path for induced current to flow away. As a result, the induced currents flow in concentric circular paths. As these electric currents resemble eddies of water, these are known as Eddy currents. They are also called Foucault currents.

\(\oint _l\vec{B} \cdot \overrightarrow{d l}=\mu_{o} i_{\text {c }}+\mu_{o} \varepsilon_{o} \frac{d}{d t} \oint _s \vec{E} \cdot \overrightarrow{d A}\)

The alignment of the dipole moments of the permanent or induced dipoles in the direction of applied electric field is called polarisation.

Electric field lines are a set of continuous lines which represent the electric field in some region of space visually.

Seebeck discovered that in a closed circuit consisting of two dissimilar metals, when the junctions are maintained at different temperature an emf is developed.

Electrical resistivity of a material is defined as the resistance offered to current flow by a conductor of unit length having unit area of cross section.

Yes, It is possible for two lens to produce zero power.
Explanation:
when the two lens (one is concave & another one is convex lens) are combined together, the focal length of the combination of the two lenses is F.
Then
\(\frac{1}{F}=\frac{1}{f_{1}}+\frac{1}{f_{2}} \)
\(\text { if } f_{1}=f_{2}=f \)
\(f_{1}=f(\text { convex }) \)
\(f_{2}=-f(\text { concave) } \)
\(P=\frac{1}{F}=\frac{1}{f}-\frac{1}{f}=0 . \ P \rightarrow \text { power } \)

(i) Pile of plates makes use of Brewster's law to convert the partially polarised refracted light into plane polarised light.
(ii) It consists of several plates kept one behind the other at an angle 90° - i_p with the horizontal surface as shown in Figure.
(iii) This arrangement ensures that the parallel light falls on these plates at i_p. When this unpolarised light passes successively through these plates, the few parallel vibrations to the surface which may be present in the refracted light, get a chance for further reflections at the succeeding plates.
(iv) Thus, both the reflected and the refracted lights are found to be plane polarised.
Uses :
The pile of plates is used as a polarizer and also as an analyser.