Answer:
b)
Explanation:
By convention, the electric field lines (which are tangent to the direction of the electric field at a given point) always begin at positive charges, and finish at negative charges.
This is a consequence of the convention that states that the electric field has the direction of the trajectory of a positive test charge when released from rest in an electric field.
(As the positive charge would move away from positive charges and would be attracted by negative ones).
So, the combination of answers that is true is b) (positive, negative, positive).
(a). If the temperature of a substance is increased the density of it will also increased. The temperature is directly proportional to the density because the molecular activity of the substance will be affected by the temperature
(b).The mass of the substance doesn't at all. Because the amount of matter inside the substance cannot be affected by the temperature except that its water
The magnetic field at center of circular loops of wire is 3.78 x 10¯⁵ T.
We need to know about the magnetic field at the center of circular loops of wire to solve this problem. The magnetic field at the center can be determined as
B = μ₀ . I / 2r
where B is magnetic field, μ₀ is vacuum permeability (4π×10¯⁷ H/m), I is the current and r is radius.
From the question above, we know that:
r = 4 cm = 0.04 m
I = 1.7 A
By substituting the parameter, we get
B = μ₀ . I / 2r
B = 4π×10¯⁷ . 1.7 / (2.0.04)
B = 2.67 x 10¯⁵ T
Due to the perpendicular plane of loops, the total magnetic field at center will be
Btotal = √(2(B²))
Btotal = √(2(2.67 x 10¯⁵²))
Btotal = 3.78 x 10¯⁵ T
Find more on magnetic field at: brainly.com/question/7802337
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C. a longer wavelength; if you look at the electro magnetic spectrum of light you will see why
