Answer:
24.71 mm
Explanation:
Distance is proportional to focal length, so
d∝f
which means

Magnification of first lens

and

Similarly, magnification of second lens

and

From the above equations we get

and

which means,

and

So, we get

∴ Focal length should this camera's lens is 24.71 mm
His lawn defies gravity alone with the way human body works
The total resistance of several resistors in series is their sum.
In this series circuit, it's (20 + 30 + 40) = 90 ohms .
Current = (voltage) / (resistance
Current = (20 V) / (90 ohms)
Current = 2/9 Ampere (0.222... A)
Answer:
Explanation:
During an energy transfer, the collision loss for an electron can be determined by using the formula:

However; from the total stopping power & power loss of the electron;

where;
Z = atomic no. for lead = 82
E = 1.9 MeV
∴
radiational energy loss = collisional energy loss 
= 0.19475
b)
Normally, the traditional lead shielding in its pure shape contains high brittleness. However, the functionality of this carbon group chemical element is useful for protection because it has an excessive density.
Initially, the conventional lead protection however reduces the mild clarity at the same moment as plexiglass is useful for light transmittance and readability.
Moreover, the traditional lead with its high density and thickness reduces observation features, in the meantime, the plexiglass is a whole lot higher than the stated.
Finally, plexiglass contains a high dimensional balance with an excessive dielectric constant.
Answer:
48 seconds
Explanation:
Since S=d/t, plug in the known values and solve
0.25m/s=12m/t
0.25m/s*t=12m
t=12m/0.25m/s
t=48 seconds