Answer:
Explanation:
electron attraction between electron and nucleus = centripetal force of the orbiting electron
In fact, Bohr model depicts the atom as a nucleus surrounded by electrons in circular orbit around it, similar to the planets around the Sun. The centripetal force that keeps the electrons in circular motion around the nucles is provided by the electrostatic force between the electrons and the nucleus.
four seasons, each lasting for about 21 earth years
summer has sun the entire time, while the winter is in full darkness
spring and autumn have a day night cycle
Answer:
19.6 cm.
Explanation:
From the question given above, the following data were obtained:
Focal length (f) = 13.8 cm
Magnification (M) = +2.37
Object distance (u) =.?
Next, we shall determine the image distance. This can be obtained as follow:
Magnification (M) = +2.37
Object distance (u) = u
Image distance (v) =?
M = v / u
2.37 = v / u
Cross multiply
v = 2.37 × u
v = 2.37u
Finally, we shall determine the object distance. This can be obtained as follow:
Focal length (f) = 13.8 cm
Image distance (v) = 2.37u
Object distance (u) =.?
1/v + 1/u = 1/f
vu / v + u = f
2.37u × u / 2.37u + u = 13.8
2.37u² / 3.37u = 13.8
Cross multiply
2.37u² = 3.37u × 13.8
2.37u² = 46.506u
Divide both side by u
2.37u² / u = 46.506u / u
2.37u = 46.506
Divide both side by 2.37
u = 46.506 / 2.37
u = 19.6 cm
Thus, the lens should be held at a distance of 19.6 cm.
Answer:
Explanation:
The problem is based on resolving power of instruments . Resolving power of instruments is related to wavelength of light as follows
resolving power of telescope ∝ 1 / λ
Higher the resolving power closer the object that can be looked separately.
Wave length of blue light is shorter than that of red light so resolving power in case of blue light will be higher. So we have better chance of distinguishing separate bulbs when color light is blue.
(a) 7.18
The electric field within a parallel plate capacitor with dielectric is given by:
(1)
where
is the surface charge density
k is the dielectric constant
is the vacuum permittivity
The area of the plates in this capacitor is
while the charge is
So the surface charge density is
The electric field is
So we can re-arrange eq.(1) to find k:
(b) 
The surface charge density induced on each dielectric surface is given by
where
is the initial charge density
k = 7.18 is the dielectric constant
Substituting,
And by multiplying by the area, we find the charge induced on each surface:
