A wavelength is the distance
between two identical peaks, troughs or crests in a wave. The unit of
wavelength can be meters, centimeters, millimeters, nanometers and so on.
(a) 25lx
(b) 11.11lx
<u>Explanation:</u>
Illuminance is inversely proportional to the square of the distance.
So,

where, k is a constant
So,
(a)
If I = 100lx and r₂ = 2r Then,

Dividing both the equation we get

When the distance is doubled then the illumination reduces by one- fourth and becomes 25lx
(b)
If I = 100lx and r₂ = 3r Then,

Dividing equation 1 and 3 we get

When the distance is tripled then the illumination reduces by one- ninth and becomes 11.11lx
Answer:
9 cm.
Explanation:
The energy used for stretch the spring from
to
will be ,
The energy used for stretch the spring from
to
will be ,
using the energy of spring formula ,we find that


Dividing both the equation will get,

Therefore, the natural length of the spring is, 9 cm.
Dependent on what you are measuring and what took you are using. Please be more specific.
Answer:
a) f=0.1 Hz ; b) T=10s
c)λ= 36m
d)v=3.6m/s
e)amplitude, cannot be determined
Explanation:
Complete question is:
Determine, if possible, the wave's (a) frequency, (b) period, (c) wavelength, (d) speed, and (e) amplitude.
Given:
number of wave crests 'n'= 5
pass in a time't' 54.0s
distance between two successive crests 'd'= 36m
a) Frequency of the waves 'f' can be determined by dividing number of wave crests with time, so we have
f=n/t
f= 5/ 54 => 0.1Hz
b)The time period of wave 'T' is the reciprocal of the frequency
therefore,
T=1/f
T=1/0.1
T=10 sec.
c)wavelength'λ' is the distance between two successive crests i.e 36m
Therefore, λ= 36m
d) speed of the wave 'v' can be determined by the product of frequency and wavelength
v= fλ => 0.1 x 36
v=3.6m/s
e) For amplitude, no data is given in this question. So, it cannot be determined.