Answer:
Explanation:
Given that,
The distance between two spheres, r = 25 cm = 0.25 m
The capacitance, C = 26 pF = 26×10⁻¹² F
Charge, Q = 12 nC = 12 × 10⁻⁹ C
We need to find the work done in moving the charge. We know that, work done is given by :
Put all the values,
So, the work done is 
.
Answer:
1) f= 8.6 GHz
2) t= 0.2 ms
Explanation:
1)
- Since microwaves are electromagnetic waves, they move at the same speed as the light in vacuum, i.e. 3*10⁸ m/s.
- There exists a fixed relationship between the frequency (f) , the wavelength (λ) and the propagation speed in any wave, as follows:
- Replacing by the givens, and solving for f, we get:
⇒ f = 8.6 Ghz (with two significative figures)
2)
- Assuming that the microwaves travel at a constant speed in a straight line (behaving like rays) , we can apply the definition of average velocity, as follows:
where v= c= speed of light in vacuum = 3*10⁸ m/s
d= distance between mountaintops = 52 km = 52*10³ m
⇒ t = 0.2 ms (with two significative figures)
It takes 365 1/4 days for the Earth to complete 1 full revolution.
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Answer:
100cm
Explanation:
Since the eyes are 6 cm below the top of her head, the point of incidence of the ray must be
200cm-3cm=197cm
Since the eyes are 194 cm from her feet, the point of incidence of this ray must be
194cm/2=97cm
So the lower edge of the mirror must be 97 cm from the ground and the vertical dimension of the mirror must be 197 cm - 97 cm = 100 cm, which is half the height of the person.
