Alternating current (AC) flows half the time in one direction and half the time in the other, changing its polarity 120 times per second with 60-hertz current.
Explanation:
Fe₂O₃ + CO → Fe₃O₄ + CO₂
Balancing the equation above, we can derive simple mathematical equations that are very easy to solve.
aFe₂O₃ + bCO → cFe₃O₄ + dCO₂
a,b,c and d are the coefficients needed to balance the equation above;
Conserving Fe; 2a = 3c
O: 3a + b = 4c + 2d
C: b = d
let a = 1;
c = 
Since b = d
3a + d = 4c + 2d
3a = 4c + 2d - d
3a = 4c + d
a = 1, c = 
3 = 4 x
+ d
d = 
b = 
multiplying a, b, c and d by 3:
a = 3 b = 1 c = 2 and d = 1
3Fe₂O₃ + CO → 2Fe₃O₄ + CO₂
Learn more:
Balanced equation brainly.com/question/2612756
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Answer:

Given:
Initial velocity (u) = 30 m/s
Final speed (v) = 0 m/s
Acceleration (a) = - 1.5 m/,s²
To Find:
Time in which train will come to rest (t).
Explanation:

So,
Time in which train will come to rest = 20 seconds
Answer:
option D
Explanation:
given,
A conductor is carrying current = 2.0 A is 0.5 mm thick
Hall voltage = 4.5 x 10-6 V
uniform magnetic field = 1.2 T
density of the charge = n =?
hall voltage =


n = 6.67 × 10²⁷ charges/m
hence the correct answer is option D
Answer:

Explanation:
For sound waves we have v=d/t where v is the speed of sound and d the distance between the astronauts, while for electromagnetic waves we have c=D/t where c is the speed of light and D the distance between the spaceship and Earth. <em>We have written both times as the same</em> because is what is imposed by the problem, so we have t=d/v=D/c, which means:

And for our values:
