Answer:
500.3 Bq
Explanation:
From the formula;
0.693/t1/2 = 2.303/t log (Ao/A)
Where;
t1/12 = half life = 5 years
Ao = initial activity = 2000 Bq
0.693/5 = 2.303/10 log (2000/A)
0.1386= 0.2303 log (2000/A)
0.1386/0.2303 = log (2000/A)
0.6018 = log (2000/A)
(2000/A) = Antilog (0.6018)
(2000/A) = 3.9976
A = 2000/3.9976
A = 500.3 Bq
Power of the glasses required is given as +2.5 D
this shows that person is having Farsightedness in which he can objects placed far clearly but he is not able to see clearly to the near objects
For normal vision near point of eye is 25 cm
Let say person can see the objects clearly at distance "d" from the eye
now from the formula
here given that
also we know that
from above equation now
So the distance of object must be 66.6 cm
Question: calculate their densties in Si unit.
200mg,0.0004m³
Answer:
0.5 kg/m³
Explanation:
Applying,
D = m/V........................ Equation 1
Where D = density, m = mass, V = volume.
From the question,
Given: m = 200 mg = (200/1000000) kg = 2.0×10⁻⁴ kg, V = 0.0004 m³ = 4.0×10⁻⁴ m³
Substitute these values into equation 1
D = (2.0×10⁻⁴ kg)/(4.0×10⁻⁴)
D = 2/4
D = 0.5 kg/m³
Hence the density in S.I unit is 0.5 kg/m³
The answer is A 0 degrees is the freezing point of water
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Answer:
iv) It is 9x bigger than before
Explanation:
As the amplitudes of the new speakers add directly with the original one, taking into account the phase that they have, the composed amplitude of the sound wave is as follows:
At = A + 4A -2A = 3 A
The intensity of the wave, assuming it propagates evenly in all directions, is constant at a given distance from the source, and can be expressed as follows:
I = P/A
where P= Power of the wave source, A= Area (for a point source, is equal to the surface area of a sphere of radius r, where is r is the distance to the source along a straight line)
For a sinusoidal wave, the power is proportional to the square of the amplitude, so the intensity is proportional to the square of the amplitude also.
If the amplitude changes increasing three times, the change in intensity will be proportional to the square of the change in amplitude, i.e., it will be 9 times bigger.
So, the statement iv) is the right one.
