(i) They are transverse in nature, and travel with the speed of light in vacuum
(ii) The selfless attitude of the scientist, service mindedness and modesty.

(a) Concern for society/nation, awareness about global warming.
(b) Applications of infared waves: To treat muscular strain, solar water heaters & cookers.

(a) Sun is the main source of UV rays.
(b) They can cause skin cancer when exposed for a longer time.
(c) Clarity in explaining, health, awareness, knowledge.

(a) X-rays are produced by bombarding a metal target by high energy electrons.
(b) To study the atomic structures, treatment for certain forms of cancer.
(c) Presence of mind. alertness, taking initiative, helpful, caring.

Hertz Experiment: Hertz's experiment was based on the fact that an oscillating electric charge radiates electromagnetic waves and these waves carry energy which is being supplied at the cost of K.E.of the oscillating charge.
Hertz Apparatus: The experimental arrangement used by Hertz for the production and detection of electromagnetic waves in the laboratory, is shown in fig. His experimental arrangement consists of two metal sheets P₁ and P₂ These sheets are connected to a source of very high voltage (i.e. an induction coil, which can supply a potential difference of several thousand volts). S₁ and S₂ are o metal spheres connected to the metal sheets P₁ and P₂ The distance between the metal sheets is kept nearly 60 cm and that between the sphere is normally from 2 cm to 2.5cm.
The two plates P_I and P₂ form a capacitor of very low capacitance (C). The circuit containing P₁ and P₂ (being completed by conducting wire), has also some low value of inductance L. It thus forms an LC-circuit. Detector (D) consisting of a coil to the ends of which two other small metal spheres S₁ and S₂ are connected.
  
Working of Hertz apparatus: Due to existence of very high voltage, air present in the gap across the plates or spheres S₁ and S₂ gets ionised. Due to presence of the ions or charged particles, the path between the spheres S₁ and S₂ become conducting. As a result of this, very high time-varying current flows across the gap between S₁ and S₂ (as plates P₁ and P₂ from an LC circuit). Due to this a spark is produced. Since, sheets P₁, P₂ from an LC-circuit, hence, electromagnetic waves of frequency 
\(f=\frac { 1 }{ 2\pi } \sqrt { \frac { 1 }{ LC } } \) are radiated.
Function of the detector D: Hertz detected the electromagnetic waves by means of a detector D, kept suitable distance from the conducting spheres S₁, S₂ . Detector D is made of two similar conducting spheres and joined to the ends of a coil to form another LC circuit. The frequency of this LC circuit is made equal to the frequency of electromagnetic waves reaching it. The frequency can be adjusted by changing the diameter of the coil of the detector and by changing the distance between S₁ and S₂ are normal to the plane of coil (C). When magnetic lines of force cut the detector coil, an emf is inducd in it.Hence, air in between ga gets ionised. A conducting path becomes available for the induced current to flow across the gap. Thus, the spark is produced between S₁ and S₂. Hertz also observed that the spark across the gap was the greatest when S₁, S₂ were parallel to each other. This clearly established that electromagnetic waves produced were polarised i.e.
\(\vec { E } \) and \(\vec { B } \) always lie in one plane.

(i) The frequency of ultraviolet rays \(({ v }_{ uv }) \) is \(8\times { 10 }^{ 14 }Hz \ to \ 5\times { 10 }^{ 16 }Hz\) . The frequency of infrared rays \(({ v }_{ IR })\) is.\(3\times { 10 }^{ 11 }Hz \ to \ 4\times { 10 }^{ 14 }Hz\) As energy, E = hv, so ultraviolet rays are much more energetic than infrared rays.
(ii) A flower plant is very delicate. It can not tolerate the exposure of high energy rays. As ultraviolet rays are of higher energy than infrared rays, therefore, The plants exposed to ultraviolet rays were damaged. And the plants exposed to infrared rays had a beautiful bloom
(iii) This study implies that small children are like flower plants. They require soft and gentle care by their mothers. Exposure of young kids to harsher treatment  is dangerous and it must be avoided 

Here, I = 3.0 x 10¹⁴ M m^-2 , E₀ = ?, B₀ = ?
Intensity of the plane electromagnetic wave is
\(I={ u }_{ av }c=\frac { 1 }{ 2 } { \epsilon }_{ 0 }{ E }_{ 0 }^{ 2 }c\)
\(\therefore { E }_{ 0 }=\sqrt { \frac { 2I }{ { \epsilon }_{ 0 }c } = } \sqrt { \frac { 2\times 3\times { 10 }^{ 14 } }{ \left( 8.85\times { 10 }^{ -12 } \right) \times \left( 3\times { 10 }^{ 8 } \right) } } \)
= 4.75 x 10⁸ V m^-1
\({ B }_{ 0 }=\frac { { E }_{ 0 } }{ c } =\frac { 4.75\times { 10 }^{ 8 } }{ 3\times { 10 }^{ 8 } } =1.58T\)

\(C=2.0\mu F=2\times { 10 }^{ -6 }F,\)
\(\frac { dV }{ dt } =6V{ s }^{ -1 }\)
Displacement current,
\({ I }_{ D }={ \epsilon }_{ 0 }A\frac { dE }{ dt } ={ \epsilon }_{ 0 }A\frac { d }{ dt } \left( \frac { V }{ d } \right) \)
\(=\frac { { \epsilon }_{ 0 }A }{ d } \frac { dV }{ dt } =C\frac { dV }{ dt } \)
\(=\left( 2\times { 10 }^{ -6 } \right) \times 6=12\times { 10 }^{ -6 }A\)
\(=12\mu A\)

Given \(A=(0.3\times 0.15){ \quad m }^{ 2 }\) 
\(d=2.0 \ mm \ =2\times 10^{ -3 } \ m\) 
\( I=100mA=0.1A\)
Since 
\(I=\frac { dq }{ dt } =\frac { d }{ dt } (CV)\)
\(=\frac { d }{ dt } \left( \frac { \varepsilon _{ 0 }A }{ d } V \right)\)
\(=\frac { \varepsilon _{ 0 }A }{ d } .\frac { dV }{ dt } \)
or \(\frac { dV }{ dt } =5\times 10^{ 8 }Vs^{ -1 }\) 
And \(I_{ D }=I\) 
so \(I_{ D }=0.1A.\) 

Given :\({ I }_{ D }=2A,\ C=3 \ \mu F=3\times { 10 }^{ -6 }F\) 
The displacement current is given by
\({ I }_{ D }=\varepsilon _{ 0 }\frac { d\phi _{ e } }{ dt } \) 
\(=\varepsilon _{ 0 }\frac { d }{ dt } (EA)\)
\( =\varepsilon _{ 0 }\frac { d }{ dt } \left( \frac { V }{ d } A \right) \)
\( =\frac { \varepsilon _{ 0 }A }{ d } \frac { dV }{ dt } =C\frac { dV }{ dt } \)
\(\therefore \frac { dV }{ dt } =\frac { { I }_{ D } }{ C } =\frac { 2 }{ 3\times 10^{ -6 } } \) 
\(=6.67\times 15^{ 5 }Vs^{ -1 }\)
Thus to set up an instantaneous displacement current of 2.0 A between the plates of the current, the potential difference across the plates should be changed at the rate \(6.67\times 10^{ 5 }Vs^{ -1 }\)