Physics — Semester B Practice

Question 1 of 10

TEKS 2Easy Word

The SI unit of electric current is:

AAmpere

BVolt

CWatt

DCoulomb

Explanation

📌 The ampere (A) is the SI unit of current. 1 A = 1 C/s. Distractor A: coulomb is charge; C: volt is potential; D: watt is power.

Question 2 of 10

TEKS 5Medium Calc Word Diagram

The diagram shows energy levels of an atom. An electron transitions from level n = 3 to level n = 1. What happens?

AThe atom emits a photon with energy equal to E₃ − E₁

BNothing happens

CThe atom absorbs a photon of energy hf

DThe atom loses one proton

Explanation

📌 When an electron drops from a higher energy level to a lower one, the atom emits a photon whose energy = E_higher − E_lower. Frequency of the emitted photon is set by hf = ΔE. This is the origin of emission spectra. Distractor A: absorption is the reverse process; C: protons are in the nucleus, not affected by electron transitions; D: emission happens.

Question 3 of 10

TEKS 1Medium Calc Word Diagram

The diagram shows two point charges. Charge A has +4 μC and charge B has +2 μC. They are separated by 0.10 m. What is the direction of the force on charge B due to charge A?

APerpendicular to the line AB

BToward A (attractive)

CAway from A (repulsive)

DZero force

Explanation

📌 Both charges are positive (like charges). Like charges REPEL. So force on B points AWAY from A. Magnitudes are given: F = kq_A q_B/d² = (8.99×10⁹)(4×10⁻⁶)(2×10⁻⁶)/(0.10)² = 7.19 N, but the question asks direction only. Distractor A: opposite direction; C: force is nonzero; D: force is along line, not perpendicular.

Question 4 of 10

TEKS 1Easy Word

Two objects that carry positive charges are placed near each other. What is the force between them?

AZero

BAttractive

CRepulsive

DDepends on distance only

Explanation

📌 Like charges repel; unlike charges attract. Two positives push apart.

Question 5 of 10

TEKS 3Hard Calc Word Diagram

The diagram shows a straight wire carrying current I to the right, placed in a magnetic field B pointing INTO the page. What is the direction of the magnetic force on the wire?

ADownward (toward bottom of page)

BSame direction as B (into page)

CSame direction as I (along the wire)

DUpward (out of the wire, toward top of page)

Explanation

📌 Right-hand rule for F = IL × B: fingers point right (direction of I), curl into the page (direction of B), thumb points UP. Force is upward. Distractor B: opposite; C: force is always perpendicular to B; D: force is always perpendicular to I.

Question 6 of 10

TEKS 1Easy Word

Which of the following is a good conductor of electricity?

ARubber

BGlass

CWood

DCopper

Explanation

📌 Metals are conductors because their electrons can move freely. Copper is one of the most-used conductors. Wood, rubber, and glass are insulators.

Question 7 of 10

TEKS 2Medium Calc Word Diagram

In the circuit shown, a 12 V battery drives current through two resistors in series: R₁ = 4 Ω and R₂ = 8 Ω. What is the current through R₁?

A1.0 A

B1.5 A

C3.0 A

D0.5 A

Explanation

📌 Series: R_total = 4 + 8 = 12 Ω. Current is the same everywhere: I = V/R = 12/12 = 1.0 A. Distractor A: only used R₂; C: split difference; D: forgot to add resistors (used just R₁: 12/4 = 3).

Question 8 of 10

TEKS 1Medium Calc Word Diagram

The diagram shows electric field lines around two point charges. What is the sign of each charge?

AA is −, B is −

BA is −, B is +

CA is +, B is +

DA is +, B is −

Explanation

📌 Field lines EMERGE from positive charges and CONVERGE into negative charges. In the diagram, arrows point OUT of A (so A is positive) and INTO B (so B is negative). Distractor A: both would show outward arrows; C: reversed; D: both would show inward arrows.

Question 9 of 10

TEKS 2Easy Word

A 12 V battery is connected across a 4 Ω resistor. What is the current through the resistor?

A3.0 A

B48 A

C16 A

D0.33 A

Explanation

📌 Ohm's law: I = V/R = 12/4 = 3.0 A. Distractor A: reciprocal (R/V); C: multiplied V × R; D: added V + R.

Question 10 of 10

TEKS 4Hard Calc Word Diagram

The ray diagram shows an object placed farther than 2f from a converging (convex) lens. What is TRUE of the image?

AReal, inverted, and reduced

BVirtual, upright, and enlarged

CReal, upright, and enlarged

DVirtual, inverted, and same size

Explanation

📌 Object beyond 2f of a converging lens: image is on the OPPOSITE side (real), inverted (flipped), and reduced (smaller than object). This is how a camera lens works. Distractor B: describes a magnifying glass (object within f); C: converging lens never produces upright real image; D: nonsense combination.

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