Electric bell, speaker, microphone and electric buzzers are some examples of electrical appliances with magnets
Hope it helps !!
SOME ELECTRICAL APPLIANCES ARE
Generator :- electromagnet
refrigerator :- permanent magnet
Electric motors and generators.
Doorbells and electric buzzers.
Computer hard drives.
these appliances use magnetic current
|a|=4 , |b|=3 , |c|=2
α=β=γ=120°α,β,γ are the angles between a and b, b and c, c and a respectively.
firstly, we will find the resultant(r) of vectors b3 and c2
r=∣∣b∣∣29+∣∣c∣∣24+2.∣∣b∣∣3.∣∣c∣∣2.cos β√ (r2=a2+b2+2ab cos θ ,θ is angle between a and b)
r=99+44+2.33.22.(−12)√ , where cos β =cos 120°=−12r=1+1−1√r=1
the resultant r makes an angle of 60° with both the vectors b3 and c2 as ∣∣b3∣∣=∣∣c2∣∣=1
hence r makes an angle of 180 with a as all the vectors are coplanar.
now the resultant of 34a and r
∣∣3a4+r∣∣ =9∣∣a∣∣216+|r|2+2.34|a|.|r|.cos 180°√ =9.1616+1+184.108.40.206.(−1)√ =9+1−6 √ =4√ =2
hence ,∣∣3a4+b3+c2∣∣ =2 =|c| , may be equal to the vector c