A bird takes off from the tree and after 5 s is flying at a speed of 10 m/s. Calculate
1 answer:
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Answer:
emf induced is 0.005445 V and direction is clockwise because we can see area is decrease and so that flux also decrease so using right hand rule direction of current here clockwise
Explanation:
Given data
initial circumference = 165 cm
rate = 12.0 cm/s
magnitude = 0.500 T
tome = 9 sec
to find out
emf induced and direction
solution
we know emf in loop is - d∅/dt ........1
here ∅ = ( BAcosθ)
so we say angle is zero degree and magnetic filed is uniform here so that
emf = - d ( BAcos0) /dt
emf = - B dA /dt ..............2
so area will be
dA/dt = d(πr²) / dt
dA/dt = 2πr dr/dt
we know 2πr = c,
r = c/2π = 165 / 2π
r = 26.27 cm
c is circumference so from equation 2
emf = - B 2πr dr/dt ................3
and
here we find rate of change of radius that is
dr/dt = 12/2π = 1.91 cm/s
so when 9.0s have passed that radius of coil = 26.27 - 191 (9)
radius = 9.08 cm
so now from equation 3 we find emf
emf = - (0.500 ) 2π(9.08 ) 1.91
emf = - 0.005445
and magnitude of emf = 0.005445 V
so
emf induced is 0.005445 V and direction is clockwise because we can see area is decrease and so that flux also decrease so using right hand rule direction of current here clockwise
Answer:
860.6 years.
Explanation:
The parameters given are;
Initial detector activity = 370000 alpha decays per second
Final detector activity = 93000 alpha decays per second
Formula for time to change in activity is given by the following relation;
t₉₃₀₀₀ = 2.72 × 10¹⁰ seconds = 860.6 years.