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what the amplitude of the resulting wave is when a +10 cm wave encounters a +20 cm wave, and when a +10 cm wave encounters a -20 cm wave? Do you add them like positives and negatives/ positives and positives,

what the amplitude of the resulting wave is when a +10 cm wave encounters a +20 cm wave, and when a +10 cm wave encounters a -20 cm wave? Do you add them like positives and negatives/ positives and positives,

Grade:12th Pass

2 Answers

Vasantha Kumari
askIITians Faculty 38 Points
9 years ago

Let us first recall these two ways of interference:

Constructive Interference: If two waves both have positive amplitudes meet and with equal amplitude their resulting amplitude is twice of either of individual waves.(your ex.. +10 cm and +20 cm wave.

Destructive Interference: If two waves but one with positive amplitude meets another amplitude with negative value then their resulting amplitude will be smaller than either of individual waves.(your ex.. +10 cm and –20 cm wave)

And as you rightly said the overall displacement of the wave is as easy with simple arithmetic:

Displacement of Pulse 1

Displacement of Pulse 2

=

Resulting Displacement

+1

+1

=

+2

-1

-1

=

-2

+1

-1

=

0

+1

-2

=

-1

Tip: you could also estimate the position between the various marked points and sketching the wave.( green line in the figure as shown)

Thanks & Regards,

Vasantha Sivaraj,

askIITians faculty

181-386_Interference.gif
TEJKIRAT SINGH
65 Points
9 years ago
 
Constructive
Interference:

If two waves both have positive amplitudes meet and with equal amplitude their
resulting amplitude is twice of either of individual waves.(your ex.. +10 cm
and +20 cm wave.
Destructive
Interference:

If two waves but one with positive amplitude meets another amplitude with
negative value then their resulting amplitude will be smaller than either of
individual waves.(your ex.. +10 cm and –20 

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