Uma barra bimetálica foi fixada em uma parede, em um dia de 25° C, como mostra a figura a seguir.
Sabendo que os coeficientes de dilatação do cobre e do alumínio valem, respectivamente, 1,7 - 10-
5°c-1e 2,2 - 10-5°c-1, pode-se afirmar que:
A. A barra se curvará para cima se a temperatura for menor que 25°C.
B. A barra se curvará para baixo se a temperatura for maior que 25°C.
C. A barra se curvará para baixo se a temperatura for menor que 25°C.
D. A barra se curvará para cima sempre que a temperatura for diferente de 25°C.
E. A barra se curvará para baixo sempre que a temperatura for diferente de 25°C.

Which of the following changes will result in a stronger electromagnet? a. using fewer coils of wire b. using a higher voltage c. using a shorter nail d. using a longer wire

An isolated conducting spherical shell carries a positive charge. part a which statement (or statements) about the electric field and the electric potential inside and outside the spherical shell is correct? which statement (or statements) about the electric field and the electric potential inside and outside the spherical shell is correct? electric potential inside the shell is constant and outside the shell is changing as 1/r2 both the electric potential and the electric field does change with r inside and outside the spherical shell electric potential inside and outside the shell is constant, but not zero electric potential inside the shell is constant and outside the shell is equal to zero electric field inside and outside the shell is constant (does not change with the position r), but is not equal to zero electric field inside and outside the shell is changing as 1/r (where r is the distance from the center of the sphere) electric field inside is equal to zero and outside the shell is constant, but not zero electric potential inside the shell is constant and outside the shell is changing as 1/r electric field inside and outside the shell is changing as 1/r2 electric field inside is equal to zero and outside the shell is changing as 1/r2 electric field inside and outside the shell is zero electric field inside is constant and outside the shell is changing as 1/r

Which statement correctly describes the current in a circuit that is made up of any two resistors connected in parallel with a battery? a. the current in the battery and in each resistor is the same b. the current the battery equals to the sum of the currents in the resistors c.the current in the battery is less than the current in either resistor d. the current in the battery equals to the product of the currents in the resistors